Category: Information Sources

Book For Sale – “What’s This Stone? A Photographic Collection of Finds from Gemstone Beach”

This small book, compiled by myself and Chrissy Lampitt, is not quite 50 pages long and features over 300 photos of stones found on Gemstone Beach in Southland. Its aim is to help people with identifying some of the many interesting stones found on Gemstone Beach (and elsewhere), and to appreciate their beauty and diversity.  It has a wire spiral binding and reasonably hard-wearing pages. The book was launched at a meeting of the Southland Geological and Lapidary Club two weeks ago – see “The Book Launch” for my speech. 

Cover of “What’s This Stone?”
Contents of “What’s This Stone?”
Preface.
Page 11 of “What’s This Stone?”
Page 12 of “What’s This Stone?”
Chrissy and John on Gemstone Beach on a recent winter’s day.
Size comparison with other books.
Gemstone Beach, Southland.
Gemstone Beach, Southland.
Gemstone Beach stones, a beach-level view.

It’s worth repeating something I said at the book launch: “It has taken us some years to identify some stones, and even then we can’t be sure we’ve got it right. Identification is an ongoing learning process, and sometimes we change our minds in the light of further information. So this book is kind of a report on what we currently think. It’s by no means meant to be the final word.” We are rockhounds, not geologists.  

The last two weeks have seen Chrissy and I contacting people who expressed pre-publication interest in the book, and sending out books to them. We have still not managed to message everyone, and the first print run of 100 copies has sold out. A second print run is now available. The book sells for $35, plus postage and handling in New Zealand of $7.50 non-rural or $10 rural. To get a copy, contact myself at john.tumblestone@gmail.com (I live in Whanganui in the North Island). I am currently on my way home from time spent in Southland and will reach there in a few days time, on Tuesday 29 September. Chrissy (who lives in Southland) has a contact form for book purchases on her blog here.  

September 2026 Book Launch Trip – Part 6, The Book Launch, Thursday Evening 10 September

NOTE: Parts 4 & 5 of this Series have not yet been written, but I wanted to post this out of sequence as a number of people have expressed interest in it. This is a slightly expanded (and more coherent) version of my talk at the Book Launch of “What’s This Stone? A Photographic Collection of Finds from Gemstone Beach”, co-authored by myself and Chrissy Lampitt. The Launch took place at the monthly meeting of the Southland Geological and Lapidary Club in Invercargill. About 25 people were in attendance, a nice size for the event. Thanks to all there for their warm reception. The book sells for $35 (add $7.50 for non-rural postage in NZ, add $10 for rural addresses – two or more books to the same address will also cost only one lot of postage). It is available now from me (john.tumblestone@gmail.com) and Chrissy (tumbleandpolish@gmail.com). It’s 49 pages long and 230mm by 155mm in size.    

Cover of “What’s This Stone?”

“What’s This Stone?”

This is a question that Chrissy and I have sometimes been asked on Gemstone Beach, by people who visit there and are really not sure what they should be looking for. They don’t know what a “gemstone” might look like. We also see people there with the small A4-sized laminated poster from the Riverton Aparima Museum, “Gemstone Beach – Sample Stones” (see below) – which was probably great when it was a large poster but the reduced size limits its usefulness. Its photos are relatively small and far from sharp, not showing key details such as the traces in the “Fossil Worm Castings”. It is also difficult to distinguish, for example, between what seem to be similar stones labeled “Porphyry”, “Spotted Argillite” and “Altered Volcanic & Filled Bubbles”.

Chrissy said one day that we should do something better. I thought about it, and after a while said we really needed a book. No-one else was doing it, so after some procrastination, we decided to give it a go. It took us a year to finish the task. Fools rush in, sometimes slowly, where angels fear to tread.

“A Photographic Collection of Finds from Gemstone Beach”

We are rockhounds, not geologists. We have “finds”, not a systematic collection of well-identified representative specimens. And we pick up stones we like the look of, that we want to polish, many of which we don’t know the identity of. It’s kind of a very random set that ends up in our collection bags. I’ve been walking Gemstone Beach on and off for nine years, Chrissy for seven. My TumbleStone Blog has lots of photos of stones I’ve found on Gemstone Beach, and over the past few years I’ve done a bit of research and writing on the identification of many of them. But all those images and information are scattered throughout the blog, and it’s not easy to find something among the many Posts which are ordered chronologically. A book provides the opportunity to put them into an easily retrievable and coherent form. And we’ve designed the book (type of paper and binding) so it can be taken to the beach and easily consulted there. I supplied the text and photos, and Chrissy has the skills and creativity and energy and persistence and patience and diplomacy to take them and construct a book, and take it through to publication. She also knows Gemstone Beach and its stones really well and so could check that the text was on track. We have been aware of Jocelyn Thornton’s “Gemstones” (1985) as a pioneer of a photo book of New Zealand stones – it has text and photos of different types of stones and also a few beaches (see below, left). It’s been invaluable to many rockhounds. We wanted to focus just on the one beach we know well, organise our book by stone type, and feature photos of individual stones. Ours is a self-published effort – the book is not produced by a commercial publisher. Chrissy put it together and sent it to a printer.    

“Orepuki” entry in Jocelyn Thornton’s “Gemstones” (1985).
Page 11 of “What’s This Stone?”
Page 12 of “What’s This Stone?”

Book Contents – Lots of Photos of Stones!

After a five-page Introduction about Gemstone Beach and stones and photographs, we have entries for 20 stone types. Each entry has some introductory text about the stone type followed by a number of photographs of specimens (see the pages on amygdaloidal stones above). Altogether, there are photos of 337 stones in the book. Of the 37 pages that make up the entries, text amounts to 11 pages and photos amount to 26 pages. So at least readers can enjoy looking at some photos of interesting stones if they find some of the writing less compelling. The entry on “Sapphire” is the only one where we don’t have photos of finds made by us, but there we have photos of Gemstone Beach sapphires found by other people. 

Assistance, But the Errors are Ours

Our knowledge about Gemstone Beach stones arise from many different sources, including books and websites, fellow rockhounds and members of online rockhound groups. After we had produced a near final draft of the book, we approached Tina Hughes, a friend and fellow Southland Club member, to proof-read it for us. She brought some issues to our attention and helped us improve the book’s readability. Then we sent the draft to the geologist Nick Mortimer who knows southern geology very well. He is one of the authors of “A Photographic Guide to Rocks and Minerals of New Zealand” (2011). He was Geoff Chapple’s Southland guide for Chapple’s book “Terrain: Travels Through a Deep Landscape” (2015). Nick also wrote the Geotrips page on Gemstone Beach. We asked him to comment on the geological content of the text. He was very generous with his response, sending us four pages of detailed notes. I broke his comments down into 51 different points and carefully worked through each one. We followed many of his suggestions but not all. As we say at the end of the book, the information and views in it remain ours (John and Chrissy’s), along with any misconceptions and errors.

Identification is an Ongoing Process

It has taken us some years to identify some stones, and even then we can’t be sure we’ve got it right. Identification is an ongoing learning process, and sometimes we change our minds in the light of further information. So this book is kind of a report on what we currently think. It’s by no means meant to be the final word.

A Blog Versus a Book

I started TumbleStone Blog partly as a record of my stone collection activities. Taking photos of stones I find and then posting them on the Blog means that I can always go and look at them again, even if I lose them or give them away. Whenever I do some research on a stone, I can post that on the Blog and refer back to it to refresh my memory. There are a number of advantages to a Blog compared to a book: new photos and information can be added regularly; a range of media can be included in Posts, from drone videos of beaches to music from YouTube songs; links to other online sources can be added; the sheer amount of material that can be included is very great; a lot of different beaches and stones and topics can be covered. So what are the advantages of a book like “What’s This Stone?” In a book, all the material on a particular topic is gathered together in one place – no need to waste time looking back through hundreds of Blog Posts. A book’s focus is more narrow but much easier to access. A book is in some circumstances easier to consult than the internet, especially on the beach. A book is not subject to the vagaries of internet reception, nor to the small size of a phone screen, nor to problems with light and reflections on a screen. Unfortunately a book’s contents, once printed, cannot be up-dated – but that’s where the internet cames in, to do that job. The two can complement each other effectively.   

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An Index to all the Posts in this Series is here.   

A Review of the “Rocktumbler.com” Website

This Review originally appeared in the September 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. An Index to this Series of Reviews, 12 of them to date, is here. The Southland Club’s website is here and its Facebook Page is here.      

In the July issue of this newsletter, I reviewed the website Geology.com. It is owned by a retired US geologist, Hobart King. King also owns Rocktumbler.com, and he himself has been tumble-polishing stones for more than 50 years. The website’s Home Page is headed up, “Rock tumblers, instructions, supplies, everything you need for rock tumbling!” A very long and informative “About Us” page starts: “You are buying from people who have done a lot of rock tumbling. We probably have several rock tumblers running in our warehouse while you are reading this. Every member of our staff knows how to operate a rock tumbler and has produced nice tumbled stones.” However, sales from the website can be made only within the United States.  

https://rocktumbler.com/
https://rocktumbler.com/tips/what-happens-in-a-rock-tumbler/

Ten years ago, I discovered a well-designed video clip on Rocktumbler.com about the underfilling and overfilling of a tumbler barrel and its lessons have remained with me. And I remember more recently reading their very interesting history of rock tumbling. One of King’s articles, “What Are Agate, Jasper and Chalcedony?”  is a very good discussion of these stones.

Rocktumbler.com sells high-quality rotary and vibratory rock tumblers manufactured by Thumler’s. “We don’t sell cheap plastic-barrel tumblers that make a lot of noise or imported tumblers that quit working after a few batches of rock. The tumblers we sell will last through years of proper use.” However, as explained in their “About Us” page, Rocktumbler.com sells only within the United States. This applies not only to their rock tumblers but also to their grit and polish, and their rough and polished stones (and everything else). This means that the website’s usefulness to New Zealanders is primarily the information it provides. Although we can’t buy their stones, their “Picture Identification Guide for Polished Stones and Tumbled Rocks” can answer some of our identification questions.

https://rocktumbler.com/tips/rock-tumbler-instructions/
https://rocktumbler.com/questions.shtml

Their “Tumbling Library” contains lots of useful tips and ideas. “We have spent thousands of hours over the past 20 years writing an extensive rock tumbling library. If you have a question about rock tumbling, our library probably has the answer. It is loaded with articles that will help you understand rocks, understand tumblers, and improve your rock tumbling results.” There are 12 sections in the Library. The first, “New to Rock Tumbling?”, includes basic guidelines and suggestions about such issues as how long tumble polishing takes, how noisy are the tumblers, and safe and convenient places to site a tumbler. The “Instructions” section includes trouble-shooting problems, the size of stones to tumble, burnishing, and ways of cleaning barrels. Other sections include information about grit and polish, tumbling media, rotary tumbling, vibrator tumbling, rock hounding, and stone crafts.

One of the limitations of Rocktumbler.com is its focus on Thumler’s equipment rather than the Lortone and Aussie Sapphire equipment, for example, that we usually have in New Zealand. Nevertheless, at least some of the equipment information transfers usefully to all types. This is a United States-oriented site so the section on rock hounding, for example, does not address places and issues in New Zealand.

 In conclusion, Rocktumbler.com is a reliable and informative website, well-presented, and very useful to home-based stone tumbling practitioners.  

The next Review in this Series is not yet available. The Series Index is here. 

A Review of the “Geology.com” Website

This Review originally appeared in the July 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. Below is a slightly expanded version. An Index to this Series of Reviews is here. The Southland Club’s website is here and its Facebook Page is here.  

When I’m searching online for information on a particular stone or mineral, one of the websites that often comes up is Geology.com, a US based site. Its articles tend to be very informative and well-illustrated, always including excellent photos of hand-sized specimens. In fact, a wide range of material can be found there – in its “About” page, it states: “Geology.com is one of the internet’s leading websites for Earth science articles, news about geology, and geographic information. Every day thousands of people visit Geology.com to view our map collection or to read articles about rocks, minerals, gems, and many other Earth science topics.”   

StoneSpeak Newsletter, July 2026.
First page of review article.
The Newsletter contains an ad for this coming week-end’s Club Open Day that I will be attending.

The website is owned by Hobart M. King and run as a family business. According to a Gemological Institute of America article on him, his geological interests began as a six-year-old, hunting for fossils in the limestone driveway at home, and he took up rock tumbling a few years later. He eventually gained a PhD in geology from West Virginia University and a graduate diploma from the Gemological Institute of America. He was employed for many years as a geologist at the West Virginia Geological and Economic Survey and he has also taught geology at university level, mainly at Mansfield University of Pennsylvania (“About the Author” in Geology.com). He is now retired.

Hobart M. King of Geology.com. Source: http://www.gia.edu/gia-news-research/tucson-visit-spurs-geology-professor-publisher-head-back-school.
Geology.com home page.

King became interested in the internet for teaching geology in the mid-1990s. In 2005, he found out that the Geology.com domain, originally owned by a petroleum consulting company, was up for auction. “I went home and told my wife I wanted to buy the website,” he recalls, “so we scraped together as much money as we could and actually won it in the auction” (Google Adsense article). Geology.com has become a family business, with King’s wife, sister, daughter and nephew each working in various roles. He also owns and operates RockTumbler.com (the subject of the next review).

Geology.com has an online store for a wide range of geology and stone-related goods. For example, there is an extensive offering of books on a range of topics such as  geology, rocks, minerals, gemstones and fossils. Also for sale are rock and mineral kits and tumbled stones. Unfortunately, none of these are available for sale outside of the United States.

From the beginning, King decided to accept commercial ad traffic on his websites because of the revenue it generated. He uses Google AdSense. He notes that “AdSense is about 50% of our profit and still the most profitable part of our business today” (Google Adsense article). I find that when I use the website, the ads are noticeable but not too intrusive – they tend to be down the lefthand page margin or at the bottom of the screen. Even now and then a page is interrupted by an ad that can easily be dismissed with one click. The quality of the information and illustrations of stones and minerals easily outweighs any annoyance, in my experience.

“Rocks” page, Geology.com.
“Minerals” page, Geology.com.
“Gemstones” page, Geology.com.
Part of “Rocks” page, Geology.com.
Part of Gemstones” page, Geology.com.
Article on flint, chert and jasper, Geology.com.

The “Rocks” section of Geology.com begins with links to pages of photos for igneous, metamorphic and sedimentary rocks. Then there are pages on 45 different rocks, from andesite and basalt through to shale and siltstone. This coverage is limited and maybe will be expanded in the future. Argillite, for example, is not currently included, with siltstone being the closest category. Chert is included but not jasper – through the chert page has a link to an article entitled “Flint, Chert, and Jasper: Names for Microcrystalline Quartz”.    

The “Minerals” section is a lot larger, with a list of 90, from andalusite, anhydrite and apatite all the way to vesuvianite, zircon and zoisite (which includes thulite). The “Minerals” main page also contains links to articles on such topics as fluorescent minerals, using acid for testing, mineral hardness, and streak testing. If you can’t find something in the “Rocks” or “Minerals” section, check out “Gemstones” which includes over 120 entries including amethyst, nephrite and even dinosaur bone.

The home page lists a number of categories of “Geology and Earth Science News and Information”. Here, articles can be found on such topics as plate tectonics (15 articles), fossils (17 articles) and meteorites (19 articles). The coverage is global, not focused just on material from the United States.

In conclusion, Geology.com content is written by a specialist in geology and gemology but with non-specialists firmly in mind. It covers some technical detail relating to a rock or mineral but I find that it is always explained clearly and technical jargon is avoided. Usually I wish a bit more information had been included but what is there is very useful.

The next Review in this Series is of King’s second website “Rocktumbler.com”. The Series Index is here.  

A Review of the “Geological Digressions” Website

This Review originally appeared in the June 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. Below is a slightly expanded version. An Index to this Series of Reviews is here. The Southland Club’s website is here and its Facebook Page is here.

When I was looking for good introductory material about trace fossils three years ago, I came across an excellent article “Someone passed this way: Tracks, trails, impressions, and footprints” on the “Geological Digressions” website. I liked the turn of phrase used there: “Trace fossils are what is left of the activity of some ancient critter”. It turned out that the site is produced by a retired New Zealand geologist, Brian Ricketts.  

Home Page of “Geological Digressions” http://www.geological-digressions.com.
Trace Fossils article on “Geological Digressions” http://www.geological-digressions.com/someone-passed-this-way-tracks-trails-impressions-and-footprints
From Trace Fossils article on “Geological Digressions” http://www.geological-digressions.com/someone-passed-this-way-tracks-trails-impressions-and-footprints

Ricketts first studied geology at the University of Auckland in the early 1970s and did his doctoral degree in the Canadian Arctic. He then worked for the Geological Survey of Canada (GSC) for a few years. “I quit the GSC in 1997 and moved with my Canadian family back to Aotearoa–New Zealand to work a 4-year teaching stint at the University of Waikato.” But “with an evolving disenchantment of academia, I decided to form my own consulting company in 2005 – a company of one – and never looked back!” (quotes taken from “A Geological Life” on the website). During his time as a geologist, he also worked in Hungary, Chile, Australia, USA, the United Kingdom and the Netherlands. Retired now, Ricketts spends time on his Waikato organic kiwifruit orchard but also continues the development of “Geological Digressions”. More details on his background can be found in “A Geological Life”.

Ricketts started his website in December 2015. He states there that “I do this for the love of it. I do not receive any remuneration for the site (and I don’t advertise). The website is not attached or beholden to any organization.” The main part of the site is a “Virtual Classroom” containing material on sedimentology, stratigraphy, volcanology, geological structure, sedimentary basins, petrography and petrology – this is aimed primarily at university undergraduate students. There is a lot of material here – 23 Main Sections, each with numerous articles – and often useful links are made to other sources as well as related pages in “Geological Digressions”.  

“Virtual Classroom” Page http://www.geological-digressions.com/how-to-do-field-tasks.
“Bivalve morphology for sedimentologists” http://www.geological-digressions.com/bivalve-morphology-for-sedimentologists
“Ripple Lithofacies – Ubiquitous Bedforms” http://www.geological-digressions.com/ripple-lithofacies-ubiquitous-bedforms.

For example, in the Virtual Classroom Main Section “Minerology of Sandstones”, there are 20 articles, one of which is on “Bivalve morphology for sedimentologists”. It looks at bivalve fossils in detail, including their external and internal morphology, and shell orientation, with well-labelled illustrations. One of the other Main Sections is “Lithofacies”. Lithofacies refers to the physical and compositional characteristics of a sedimentary rock unit or sediment layer. There are 41 articles in the Section, one of them being “Ripple Lithofacies – Ubiquitous Bedforms”. It describes how ripples are formed on sedimentary surfaces and their different characteristics.   

This “Virtual Classroom” is an excellent resource for people who have not formally studied geology – here you can get access to some of the material that is presented to university students. Yes, it can be technical, but it is well presented and a treasure for the keen learner.

Other articles in “Geological Digressions” are written with non-specialist or non-technical people in mind. Across the top of the site’s pages are links to four groups of articles: Glossary, Atlas of Sediments, Ancient Earth, and More. There are 11 glossaries (alphabetical lists of technical terms with their meanings), on topics including Stratigraphy, Sedimentary Structures, Volcanics, and Palaeontology. Alongside the explanations of key terms are links to any website articles relevant to them. “Atlas of Sediments” is a collection of photos that Ricketts has accumulated. There are 24 groupings here. One of them, for example, is “Atlas of Trace Fossils” which has 33 photos of different trace fossils, some from New Zealand.

One of the Glossaries http://www.geological-digressions.com/glossary-paleontology.
“Ancient earth. 2 How old is it?” http://www.geological-digressions.com/ancient-earth-how-old-is-it.
Sandstone formation http://www.geological-digressions.com/from-sand-to-stone-sandstone-a-remarkable-transformation.

The “Ancient Earth” heading takes you to 13 articles. The second one asks how old the Earth is. Here, Ricketts looks at a number of people in history who have attempted answers. He then refers to the search for the oldest rocks on Earth and what they imply. Another “Ancient Earth” article is on stromatolites, the earliest physical life form on Earth. Under the “More” heading are 14 other topics, some of which contain a lot of different articles. For example, “Interpreting Earth” has 28 articles, ranging from how sand gets turned into stone to understanding how a fossil forest in the Arctic has survived.

As you can see, “Geological Digressions” is large, detailed, diverse and wide-ranging, containing both technical and non-technical geology-related information broadly defined. The Home Page refers to “436 articles” being there. In general, these are well-written and have lots of interesting detail and illustrations. You can use the “Search” function to look for something specific. Or you can take a stroll along its many corridors, exploring whatever takes your fancy.

The next Review in this Series is of the “Geology.com” website. The Series Index is here. 

A Review of Three Kiwi YouTube Rockhounds

This Review originally appeared in the April-May 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. Below is a slightly expanded version. An Index to this Series of Reviews is here. The Southland Club’s website is here and its Facebook Page is here.

Anyone can used their phone camera to take photos and make video clips of their activities and post them on social media. Facebook, Instagram and YouTube are popular outlets and some rockhounds have not been reluctant to use them. They provide a great way to store images of a find or a fossick that you can go back to anytime to enjoy. And other people can enjoy and learn from them too. Here is a review of how three New Zealanders have used YouTube to store and share their videos of stones and fossils.

Nicola Gray, who lives in Hastings, Hawkes Bay, has a Facebook Page and YouTube channel, and she is active on a number of Facebook Rockhound Groups. Her YouTube channel “New Zealand Rockhound” documents many of the details of her fossicking and tumble-polishing, as well as stone cutting and craftwork. Introducing herself on YouTube, Nicola states: “I love rock hunting, and especially love sharing my finds with others. I really enjoy sharing my rock tumbler barrel washouts. I make beautiful pendants from my stones too.” For Nicola, making and editing and posting videos are a regular and natural part of being a rockhound.

Nicola Gray’s YouTube Channel http://www.youtube.com/channel/UCSQMZ5-H0nsBL_bM2BjNEHw/videos.
Nicola Gray’s videos.
More of Nicola Gray’s videos.

I first met Nicola when she travelled south with Angie Nicholas to visit Gemstone Beach in April 2023. At the time I was nearing the end of my “Southern Sojourn” on the south coast. Our first joint fossick there is described by me in this Post and this Post, with two further fossicks described here and here. Nicola’s own video of visiting Gemstone Beach can be found here – it is just over eight minutes long and has been viewed over 3,100 times.

At the time I wrote this Review, in early April 2026, Nicola’s channel contained 479 videos and had 1,130 subscribers. I went through her latest 50 videos to identify their content. I found that in 12 of them, Nicola was showing different types of stones, sometimes recently arrived in the mail from other people, sometimes recently tumbled/cut or about to be tumbled/cut. Another 12 of her latest 50 videos showed Nicola washing out a tumble barrel or vibratory tumbler. Nine showed her cutting stones, and eight recorded her looking for stones on a beach somewhere in New Zealand (such as in Hawkes Bay, on the south coast including Gemstone Beach, and the West Coast). The other nine videos were on topics such as loading a tumbler barrel, tumbling advice, and a microscopic view of a stone.

At the top of the list of videos on a YouTube channel, you can click on “Latest”, “Popular” and “Oldest” to help you move among them in different ways. Nicola’s most popular video, viewed 30,878 times, is a short 33 second clip posted in October 2020 recording her discovery of a storm jasper in the Tukituki River. Most of Nicola’s videos are between about three minutes and 12 minutes in length with only the odd one lasting more than 20 minutes. So, in many ways, they are snapshots into the daily life of a rockhound who cuts and polishes her finds.

Gordon Sherwood and his wife Beth have a crystal and wellness shop in Edgecumbe, Bay of Plenty, called Heaven’s Ascent. Gordon has a Facebook Page under the title of “New Zealand Rocks Downunder” which is also the name for his series of YouTube videos. He introduces himself as follows: “I live in the Eastern Bay of Plenty, and have to travel to other areas for older rocks that contain interesting specimens.  You can expect to accompany me as I find interesting rocks, fossils, and uncover some of the interesting insect life here in New Zealand. Look out for my attempts at cutting and carving the rocks that I have found as I get the gear together to do it… Our retail shop has a great selection of crystals and gemstones that fuels this passion to fossick, which is squeezed in whenever I can, going AWOL without getting in too much trouble with the Mrs.” In July 2025, Gordon and Beth featured in an Eastern Bay article celebrating National Tartan Day.

Gordon Sherwoods YouTube Channel http://www.youtube.com/@NewZealandRocksDownunder/videos.
Gordon Sherwood’s videos.
Source: https://easternbayapp.co.nz/news/articles/6865b5eb80a872f72cee39b5

Gordon has had some health issues which sometimes delays new postings. However, at the time I wrote this Review, his YouTube channel contained 138 videos and had 2,030 subscribers. His most popular video, “Uncovering the Secrets of Gemstone Beach” (33 minutes long), was posted in August 2023 and has been viewed 48,315 times. Gordon’s videos tend to be longer than Nicola’s, usually between 15 and 30 minutes. There is more of a narrative to each piece and they are often quite informative about a stone type or fossicking place. Some topics are: excavating microfossils at Matata Beach (a favourite destination), visiting the Tauranga Gem and Mineral Club 2024 Show, searching for pounamu greenstone at Jackson Bay, looking for pakohe (a traditional stone used for tool making and carving), fossicking at Birdlings Flat, and fossil hunting at Motunau Beach.

The third YouTube user is Morne of “Mamlambo Fossils” whose first video was posted in May 2019. He has become very well-known: Newsweek had an article on “Morne Mamlambo” in June 2021; TV1’s Seven Sharp had a five-minute feature on him, shot on Motunau Beach, in November 2024 , reporting that he had rented a hall at the old Waikuku School in Canterbury as a workshop, fossil museum and educational centre; and on 30 March this year RadioNZ interviewed him in their Monday Afternoon Expert segment.

Morne, who declines to give his surname, is a software engineer and grew up in South Africa. He introduces himself as follows: “I’m an amateur fossil hunter living on the South Island of New Zealand. I enjoy hunting the coastal cliffs for Miocene and Cretaceous era fossils and venturing further afield for the petrified wood and fossils that can be found there. I’m constantly learning about the fossils that can be found here in New Zealand. I also use a variety of tools and techniques to prepare the fossils I find which I then donate to New Zealand museums.” He has taken the name “Mamlambo” from a mythical South African creature which has the head of a horse, the lower body of a fish, short legs, and the neck of a snake. He started off by taking videos of his finds to show his family back in South Africa and attracted quite a bit of attention when he posted them on YouTube.

Morne Mamlambo’s Fossils Channel http://www.youtube.com/@MamlamboFossils/videos.
Morne Mamlambo’s Rocks Channel http://www.youtube.com/@mamlamborocks/videos.
Guided fossil walks offered https://mamlambofossils.com/fossiltours.

Morne has a number of online and social media outlets, including a website, and he posts videos on all of these. One of the things on his website is his offer of paid guided fossil walks. At the time I wrote this Review, his “Mamlambo Fossils” YouTube channel contained 370 videos and had 611,000 subscribers. His videos record his hunts for fossils, the many hours he spends preparing them (using a variety of tools to wear away the surrounding rock), and issues around their identification. One of his most popular videos from 2021 “MONSTER fossil crab prep – the 50lbs crab finally gets prepped… and it’s a beast!” is 13 minutes long, has been viewed 2,443,525 times, and uses speeded-up photography to show the 208 hours of work he spent revealing the fossil. He has made lots of fossil finds, many of them very significant, such as a new species of billfish, now officially named Zealandorhynchus fordycei, honouring the late Ewan Fordyce, an influential University of Otago vertebrate palaeontologist.

Morne also has a second but smaller YouTube channel called “Mamlambo Rocks”. It contains 50 videos and has just over 10,000 subscribers. The most popular of these videos are on agate hunting in Canterbury. There is also a 48 minute video of most of an August 2025 talk on agates by the late Malcolm Luxton. Other videos feature petrified wood and fossicking in such places as Birdlings Flat and the Conway River.

It takes time to view a video online – you can’t just glance at it like you can a still photograph. And you don’t know how interesting or useful it will be until you’ve seen it through. But a good video can take you right into a promising rockhunting area, and show you what to look for, much more effectively than just written text. Watching a couple of their homemade videos allows you to assess if the approach of a rockhound works well for you, providing enjoyment and learning and inspiration.

“Thank you!” to these three rockhounds for sharing their passion and knowledge with us.

The next Review in this Series is of the New Zealand-based “Geological Digressions” website. The Series Index is here. 

A Review of “AlexStrekeisen” Website

This Review originally appeared in the March 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. Below is a slightly expanded version. An Index to this Series of Reviews is here. The Southland Club’s website is here and its Facebook Page is here.

When I’m doing some research on a rock or a mineral, I usually look at the relevant entry in the “AlexStrekeisen” website. Some of the information there is quite detailed and often accompanied by good photos of rocks.

Cover of “StoneSpeak” March 2026.
Page 7 of “StoneSpeak” March 2026.
Home page of http://www.alexstrekeisen.it/english/index.php
Alessandro Da Mommio. Source: http://www.alexstrekeisen.it/english/index.php

There are also microphotos of thin rock sections at the end of each entry – photos of what you’d see looking through a microscope. These are intriguing and can be quite spectacular:

Calcite and zeolite (grey) filling an amygdale. Field of view = 7mm. http://www.alexstrekeisen.it/english/vulc/amygdales.php
Fragments of various nature in a breccia, field of view = 7mm. http://www.alexstrekeisen.it/english/sedi/breccia.php
Olivine crystals in a dunite, field of view = 7mm. http://www.alexstrekeisen.it/english/pluto/dunite.php
Allanite crystals, biotite and microcline feldspar in a granite, field of view = 7mm. http://www.alexstrekeisen.it/english/pluto/allanite.php
Globigerinids Foraminifera in a Mudstone, field of view = 2mm. http://www.alexstrekeisen.it/english/sedi/mudstone.php
Hornblende, plagioclase and quartz in a type of gabbro, field of view = 7mm. http://www.alexstrekeisen.it/english/pluto/quartzgabbro.php

Alessandro Da Mommio is the Italian geologist behind this website (photo at top of Post, far right). He notes on the home page that his passion for optical petrography inspired him to create an online vehicle for “the recognition and identification of mineral phases in thin section”. The website is available in both Italian and English. If you find yourself on the Italian-language version of the site, click on the Union Jack flag just under the header to be taken to the English-language version.

The website is named after Albert Strekeisen (1901-1998), a pioneering Swiss petrologist who has been very influential in rock classification systems. The QAPF (Quartz – Alkali feldspar – Plagioclase – Feldspathoids) diagram for the classification of igneous rocks is known as the “Streckeisen diagram” in his honour (see image of diagram below, far left). Da Mommio is a geology lecturer at the University of Milan and a specialist in microphotography. Last year, with Victoria Pease he published the book “Atlas of Minerals and Igneous and Metamorphic Rocks in Thin-Section”.

“Streckeisen diagram”, the QAPF diagram for classification of igneous rocks. https://commons.wikimedia.org/wiki/File:Streckeisen_Plutonic_Rocks.svg
Rhodonite page. http://www.alexstrekeisen.it/english/meta/rhodonite.php
Rhodonite, Franklin Mine, New Jersey. http://www.alexstrekeisen.it/english/meta/rhodonite.php
Granular rhodonite crystals, field of view = 7mm. http://www.alexstrekeisen.it/english/meta/rhodonite.php

Da Mommio describes his website as follows: It is “designed for students of geology and petrography and geology enthusiasts… Each page consists of two parts, descriptive (an exhaustive explanation of the mineral phase) and visual (high-resolution photographs).” New pages on rocks and minerals are being added regularly – one of the most recent is Rhodonite which has especially colourful thin-section microphotos (see image above, far right).

The website has five main sections – on the four main types of rocks (plutonic, volcanic, metamorphic and sedimentary) and on the Italian magmatic provinces (areas of volcanic rocks). The rock sections have long lists of contents running down the left margins, arranged under a small number of headings. For example, for Metamorphic Rocks, the main headings are Metamorphic minerals, Texture and microstructure, and Metamorphic rocks. For Sedimentary Rocks, the main headings are Sedimentary rocks [main types], Turbidites, Fossils, Sedimentary minerals, Texture, and Rocks. For each entry under those headings, there is usually a description of the mineral, rock or item, often with technical detail.

Page on Metamorphic Rocks. http://www.alexstrekeisen.it/english/meta/index.php
Page on Sedimentary Rocks. http://www.alexstrekeisen.it/english/sedi/index.php
Page on Plutonic Rocks. http://www.alexstrekeisen.it/english/pluto/index.php

However, the entries vary in length and usefulness, some being quite detailed but others being quite short. A few of the entries rely heavily on Mindat.org, but most go beyond that. Unfortunately, the list of references for minerals and rocks seem to be mainly textbooks, not online sources that you can follow up. For that, you then need to go to such websites as Geology.com and Wikipedia.

The next Review in this Series is of three New Zealand YouTube rockhounds. The Series Index is here. 

A Review of “New Zealand Geographic” Magazine Online

I wrote this Review for the January-February 2026 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. The Southland Club’s website is here and its Facebook Page is here.

The most recent edition of the “New Zealand Geographic” magazine features an article called “Dragonlust”. It is introduced as follows: “Split open a chunk of agate and a broiling world of ancient colour emerges. Collecting the stuff is addictive. But with the old rockhounds fading, what will become of the last great hoards?” Among the “old rockhounds” in the article are the Canterbury agate experts Malcolm Luxton (recently deceased), John Taylor, Vince Burke (Birdlings Flat Gemstone and Fossil Museum) and Robin Hall. The article raises the question of what will happen to their finds in the future. Towards the end, Southland’s Jack Geerlings is mentioned. “Another enormous collection – the work of Jack Geerlings, a dairy farmer known for his masterful polishing work – was recently auctioned off in the wake of his death… Seven tonnes of his treasures went at bargain prices, to be absorbed into smaller collections, or sold off by rock shops to tourists.” Reading this article prompted me to take a closer look at the magazine.

Cover of “New Zealand Geographic”, November-December 2025.
“Dragonlust” article, “New Zealand Geographic”, November-December 2025.

The first issue of “New Zealand Geographic” appeared in January-February 1989, and it has been published bi-monthly since then. Warren Judd, whose rock collection was visited by Southland Club members in January, was deputy editor from 1995 to 2004 and then editor for four years. It was one of Judd’s university students, Kennedy Warne, who was founding editor. The magazine’s format is based on “National Geographic”, with great photography and interesting well-researched local stories. The focus is on the geography, biodiversity, history and culture of New Zealand, Antarctica, and nearby Pacific Islands.

In 2014, the magazine marked 25 years in print by digitising its entire back catalogue and making it available online. Anyone can access five items free each month. A $1 subscription provides access to as many articles as you want for two months (I used this while doing research for this review) – after that, a digital subscription costs $8.50 every two months. The website has a very good search function and across the top of an article is a “Related” button that takes you to another article on a similar topic. Or you can search for articles by a writer – for example, Carl Walrond has written a number of geology-related articles. The audited readership of “New Zealand Geographic” in 2024 was 387,000 readers, making it the fourth-most-read magazine in the country. It gets about a million visits a year to its website, which makes it the most-visited magazine site in New Zealand by a good margin. Every now and again it faces financial uncertainty, but its supporters and readers have always worked hard to ensure its survival.

Of course, many of the magazine’s articles deal with topics not directly related to geology, rockhounding or lapidary pursuits. But some do. Here are nine examples: “Rock Hounds” (Jan-Feb 2022) is on Nelson rockhounding and some of the issues around ownership of pounamu; “Ventifacts – Sandblast from the Past” (Nov-Dec 2004) is on stones shaped by wind-blown sand; “Touchstone” (July-Aug 2024) deals with pakohe, a type of argillite; “Pillow Talk” (Jan-Feb 2004) discusses pillow lava; there’s an article on “Gold” (Mar-Apr 2005) ; “The Day the Earth Stood Still” (Jan-Feb 2022) is an article by Warren Judd on the K-Pg boundary in North Canterbury/Southern Marlborough, the geological trace of the apocalyptic event that wiped out the dinosaurs; “Harold Wellman and the Alpine Fault” (Jan-Mar 1999) is on the first recognition of this great faultline; “Hooligan’s Gallstones” (Nov-Dec 2003) refers to the Moeraki Boulders; and “The Menhirs of Rodney County” (July-Aug 2006) describes some unusual rock forms and their geological origin. And there are many articles on what could be called “rock landscapes”, like “The Rocks of Castle Hill” (Oct-Dec 1999) about a limestone karst landscape, and “Eden in Auckland” (July-Aug 2016) about Auckland’s rock forest lava field.

One of the main strengths of “New Zealand Geographic” articles is that they are written as engaging stories. In other words, they are colourful, lively, interesting and informative. They make links to individual people, situate places in their history and culture, and provide relevant well-researched detail. And nearly all of this is local – if you live in New Zealand, you could probably visit these places if you wanted to. It is well worth trying out the introductory $1 subscription to explore for a couple of months the wealth of material in this magazine.

The next Review in this Series is of the “AlexStrekeisen” Website. A Series Index is here.

A Review of the “Sandatlas” Website

I wrote this Review for the December 2025 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. The following is a slightly fuller version. The Southland Club’s website is here and its Facebook Page is here.

I was recently doing some research about breccia for a couple of blog posts I was writing (“TumbleStone Calendar 2026: November – Breccia” and “T is for a Type of Tiny Tectonic Breccia?”). By far the best piece I found on breccia was on a website called Sandatlas. The piece is well-written, comprehensive, nicely illustrated, is not shy about being a bit technical but is generally quite readable, and it covers a wide range of relevant issues. It is not a brief piece and it doesn’t oversimplify, but it was invaluable in helping me gain a detailed overview of breccia and its formation. The accompanying photographs and diagrams are outstanding. The rest of Sandatlas is similar.

Siim Sepp. https://sandatlas.org/about
Sandatlas Home Page. https://sandatlas.org
Sandatlas page on Breccia. https://sandatlas.org/breccia

Sandatlas is the project of Siim Sepp (above, left), an Estonian who describes himself as a software developer, author, geologist, and photographer. He started Sandatlas in 2012 as a website about sand. But what started with photographing sand samples from around the world grew into a broader guide to geology. The website’s home page now states: “Sandatlas is an educational website that aims to explain geological concepts in a clear and accessible way. The content is designed for students, educators, amateur geology enthusiasts, and anyone curious about the Earth’s materials and processes. The site features illustrated articles about rocks, minerals, sand types, and key geological terms – supported by original photographs to help readers better understand the subject matter.”

One of the great things about Sandatlas is Sepp’s high-resolution photos of rocks – he often provides a good range of examples of a rock type, and they tend to be handful size or just a bit bigger, the size you find on a beach or in a river. The majority of the photos featured on Sandatlas are from Sepp’s own rock and mineral collection, assembled from numerous geological expeditions to places including Estonia, the Nordic countries, the United States, Cyprus, Morocco, France, and Ireland.

Gabbro specimen. https://sandatlas.org/gabbro/
Another gabbro specimen. https://sandatlas.org/gabbro/
A further gabbro specimen. https://sandatlas.org/gabbro/

One of the main pages on Sandatlas is “Complete Guide to Rock Types: Igneous, Sedimentary, Metamorphic”. Forty-six igneous rocks are listed, with brief descriptions, and 30 of them have links to their own page with a more detailed description and lots of interesting photos. Thirty sedimentary rocks are listed (19 having their own page), and 27 metamorphic rocks (16 with their own page). I assume Sepp intends eventually to provide pages for all the listed rock types. In general, the coverage is selective but is nevertheless impressive.

Igneous rocks. https://sandatlas.org/types-of-rocks/
Sedimentary rocks. https://sandatlas.org/types-of-rocks/
Metamorphic progression. https://sandatlas.org/metamorphic-rocks/

Another main page is “Rock Forming Minerals”. This is a very long page and is much more technical than the rock types section. It’s more like what you would find in a geology textbook, but in my view it is well organised, well explained and well illustrated. If you want to gain an understanding of the chemistry and character of something like framework silicates, or the garnet group, or corundum, this is a great place to go to. How and where minerals form is covered along with the general traits of hand specimens. Field tips, weathering and environmental notes are usually provided. These help to make the technical information more useful to the likes of you and me.

There’s a lot 0r interesting stuff on Sandatlas, although it’s not always easy to find. At the end of the home page is a list of articles that explain key geological concepts and natural processes. This includes such intriguing topics as “How Geologists Identify Rocks”, “What is Opaque Color”, and “Do Rocks Really Fit Into Three Categories?”. At the end of each article is a folder icon with one or two names of Sections in the website – if you click on these Section names, you will be taken to lists of other articles that are otherwise hard to identify.

Sandatlas article. https://sandatlas.org/how-geologists-identify-rocks/
Sandatlas on the 3 categories of rocks. https://sandatlas.org/rock-classification-problems/
Two Category Names for lists of articles at end of Sandatlas on the 3 categories of rocks. https://sandatlas.org/rock-classification-problems/

“Rocks are not silent,” writes Sepp in the “About” page of Sandatlas. “They carry the memory of oceans long vanished, volcanoes that once shook the sky, continents that drifted across the planet. Learning to read them is a way of regaining closeness to the Earth. When we look at nature with understanding rather than indifference, we begin to value it – and we protect what we value.” He continues: “Sandatlas is a bridge between curiosity and knowledge, between observation and insight. It… exists for the broad community of curious minds – hikers who pause at a cliff face, photographers drawn to patterns in stone, collectors who turn over pebbles just to know what they are. It is here for anyone who suspects that the landscapes they walk through are more than just scenery.”

The next in this Series is “A Review of ‘New Zealand Geographic’ Magazine Online“. An Index to this Series is here.

 

A Review of Jocelyn Thornton’s (1985) “Gemstones”

I wrote this Review for the November 2025 edition of “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. The following is a slightly fuller version. I previously did a brief Post on the same publication in TumbleStone Blog in April 2016. The Southland Club’s website is here and its Facebook Page is here.

Page 4 of “StoneSpeak” Newsletter, November 2025.
Page 3 of “StoneSpeak” Newsletter, November 2025.
Page 2 of “StoneSpeak” Newsletter, November 2025.
Page 5 of “StoneSpeak” Newsletter, November 2025.

Jocelyn Thornton’s booklet “Gemstones” was first published in 1985 by Reed Methuen in the Mobil New Zealand Nature Series. It was produced to be used in the field – it has slightly thicker pages than usual, a spiral binding, and it’s of a size to fit in a large pocket. It’s a guide for stone collectors, polishers and cutters to the kind of material that can be found mainly on beaches in New Zealand. Each section has photos of stones on one side, and a numbered key and description of stones on the other. It’s an invaluable resource for stone fossickers and lapidarists, and there is no comparable book around. I managed to buy a second-hand copy about ten years ago but it is now rare, and we are fortunate that it has been made available online, here and here.

Booklet cover.
Online cover http://www.onnaturesedge.co.nz/downloads/nzgemstones.pdf.
Index to online copy of Thornton’s “Gemstones”.

Jocelyn Thornton was born in Wellington, initially working as a journalist after studying English literature at university (see Micromounters Hall of Fame). In the mid-1960s, she took up rock and mineral collecting as a hobby then returned to university in 1977 to study geology. For many years she has been honorary curator of the Alexander Mackay Geological Museum at Victoria University of Wellington (see photo below, left).

Jocelyn Thornton (right) at opening of Research School of Earth Sciences, Victroia University of Wellington. 1985. https://tapuaka.wgtn.ac.nz/nodes/view/8505
https://www.baltimoremineralsociety.org/uploads/1/6/6/3/16636366/joeclyn_thornton.pdf

As well as “Gemstones”, she has written “The Field Guide to New Zealand Geology: An Introduction to Rocks, Minerals and Fossils”, also published in 1985 but revised and up-dated a couple of times since. This is a substantial publication, covering the country’s geology within a framework of geological eras but also New Zealand regions. Its photographs are taken from the road or the beach, showing formations accessible to the average traveller. It is aimed at the general public and beginners in geology.

In 2009, Thornton wrote the entry on “Gemstones” for Te Ara, the Online NZ Encyclopedia. This entry has some excellent photos of different types of stones, such as “Silicified Wood and Plant Material”, “Chert, Flint and Jasper”, and “Greywacke Pebbles with Quartz Veins”. In 2004, Jocelyn Thornton received the NZ Order of Merit for services to Earth Sciences.

To get back to Thornton’s “Gemstones” booklet: It used to be available on her husband’s website, but that disappeared in 2022. Soon after, it was posted on the information site of Tuatapere, a town in Western Southland. The site is called “On Natures Edge – Tuatapere” and its “What’s Here” section has a brief page on nearby Gemstone Beach which includes a link that brings up a pdf file of the booklet. It is now also available on the Tumble and Polish Blog.

Thornton’s “Introduction” to her booklet is very good, covering the topics of gemstones, NZ’s stones, polishing and other lapidary techniques, access issues, and equipment for beach collecting. She acknowledges assistance from various local rock and mineral clubs. There are two main sections in the booklet: 25 pages on specific types of stones, with photos, and 7 pages on stones from different areas/beaches, again with photos.

Garnet. Page 9 of Thornton’s “Gemstones”.
Petrified Wood. Page 21 of Thornton’s “Gemstones”.
More Jasper. Page 18 of Thornton’s “Gemstones”.

A wide range of stones are covered, from greenstone to quartz to jasper to petrified wood. Thornton’s comments on them refer to their characteristics and where they can be found. The regional coverage in the second section is patchy (for example, Northland is not included), sometimes quite general (one page is dedicated to the East Coast from Hawke Bay to North Canterbury) and sometimes very specific (Birdlings Flat, Slope Point and Orepuki have their own pages). If you are interested in the likes of the stones from Orepuki (Gemstone Beach), don’t just look at the page on that location – also check out the pages on the kinds of stones to be found there, such as Garnet, Jasper and Quartz.

East Coast. Page 31 of Thornton’s “Gemstones”.
Slope Point. Page 35 of Thornton’s “Gemstones”.
Orepuki (Gemstone Beach). Page 36 of Thornton’s “Gemstones”.

If you want to identify a stone and have only a vague idea of what it might be, Thornton’s “Gemstones” might be able to help you, if you slowly look through its pages. If you are visiting one of the beaches she covers, the booklet will alert you to the kinds of stones you will encounter. There is a lot of material in it and I often consult it. One of its limitations is the quality of the photographs. I often wish they were brighter or more detailed, but maybe that relates to the technology of the time and the need to keep expenses down. It also has no index, so if I’m looking for information on thulite, for instance, it’s difficult to work out if it’s in there – in fact, I don’t think it is. And that’s another limitation of the booklet, it doesn’t include all the significant stones to be found at different places. It’s selective in its coverage, maybe due to the stones that were available to Thornton to photograph. However, this doesn’t detract from its great usefulness to anyone interested in New Zealand’s stones. Like any good thing, you always wish for more.

The next Review in this Series is of the “Sandatlas” Website. An Index to this Series is here.