Category: Quartzite

January 2022, Stone of the Day #22 – A Timaru Quartzite with Windows

My first batch of polished stones from Timaru was completed on 19 January 2022. The beach that they came from is described in the Post on Stone #21, except that I accessed it at the end of Ellis Road, a little south of Scarborough Road. The actual day I found Stone #22 was Sunday 27 June 2021, on a foggy morning, and two photos of it appear in a Post on that visit. This is the polished stone, with a small number of blemishes apparent:

It is a stone with two different coloured faces, one red and the other yellow:

The other side of Stone #22, the yellow side.

One of the most interesting aspects of this stone is the “windows” into it, small clear inclusions. There are hundreds of them, many very tiny. These I have elsewhere called “entrances”. Sometimes, though not often, these can come loose in the tumbling process, and one end of Stone #22 has a hole in it from a missing window.

One end of Stone #22 has a missing “window”.
Small hole in the end of Stone #22 (on left).
Lots of “windows”, some very tiny.

Comparing the polished stone with the stone the day it was found on the beach gives an idea of the extent to which the “windows” have been reduced during the tumbling:

Stone #22 when found on beach.
Stone #22 after tumble polishing.
Stone #22 when found on beach.
Stone #22 after tumble polishing.

Stone #22 is 4.5 cms long, 2.5 cms wide and around 1 cm thick. It was put in a 400 grit tumble for 10 days followed by another 10 days in a 600 grit tumble. After 11 days in tin oxide tumble polish, it underwent a borax burnishing tumble for three days.

The carpark at the end of Ellis Road, south of Timaru.
Stones on the beach, Timaru.
The stretch of beach where I found Stone #22.

The Index to the January 2022 Stone of the Day Series is here.

January 2022, Stone of the Day #21 – A Dark Quartzite(?) from a Timaru Beach

It is the lighter-coloured stones that normally attract my eye on the beach. This stone is a particularly dark one, but the veins that criss-cross it caught my eye and a closer look suggested it might be a quartzite. I find the dark veins attractive along with the complexity of the stone.

The flashes of dark red in it add further interest:

The other side of Stone #21.

I first visited this beach near Timaru in June 2021, following up a mention of it in a Post in the “New Zealand Lapidary, Rocks, Minerals, Fossils” Facebook Group made by Sascha Stoddart. Sascha crafts with copper wire and oiled stones, as beautifully presented on her Facebook Page “Wire on the Rocks”.

Sascha Stoddart’s “Wire on the Rocks” Facebook Page https://www.facebook.com/Wireontherocks
Copper wire and oiled stones.
One of the interesting green quartzites from the Timaru area.
A petrified wood piece from the Timaru area.

As Sascha states: “Wire on the Rocks originated from the discovery of a piece of pink Rhodonite, which I found in May 2020, when walking along the beach in Timaru. Within two weeks I had found a second piece, and had developed a beach stone obsession which rapidly escalated and resulted in a growing collection of treasure. I decided to try my hand at wire wrapping some of the stones, and was soon creating jewellery and sculptures, and experimenting and exploring different ideas. In February 2021, and more than 130 creations later, I named my creative pursuit Wire on the Rocks.”

Source: https://www.facebook.com/Wireontherocks
Source: https://www.facebook.com/Wireontherocks
Source: https://www.facebook.com/Wireontherocks
Source: https://www.facebook.com/Wireontherocks
Source: https://www.facebook.com/Wireontherocks

Some of Sascha’s stones are found on the beach that can be accessed at the end of Scarborough Road, just south of Timaru. I made my first visit there in the late afternoon of 5 June 2021. Once I found the access point, after trying a couple of dead-ends, I did a quick reconnaissance of the beach and returned the next day when I found Stone #21 (see the entry for Sunday 6 June 2021 in this Post). At that time, I also found a larger quartzite of similar hue.

The beach at the end of Scarborough Road. There is a walkway along the top of the cliff.
This is the only place along the beach where a safe crossing of the railway exists.
The track between the railway crossing and the beach access.
Further along the beach, the lighthouse can be seen.
Looking north from the railway crossing towards nearby Timaru. This part of the beach is also great for fossicking.
Another, though larger, dark quartzite found on 6 June.

Stone #21 originally had a small chunk out of it (see photo below) which I smoothed away using at least a couple of tumbles with 220 grit. Using 80/100 grit would also have done the job, and more quickly, but the 220 grit tumbles gave me more control over the shaping process as I wanted to minimise the reduction in size of the stone.

Stone #21 when found on the beach.
A chunk was missing from the stone.
The final polished stone, indicating the area where the “blemish” had originally been.

I then used a 400 grit tumble followed by a 600 grit tumble to prepare the stone for polishing as best as I could. It spent 11 days in tin oxide tumble polish followed by a borax burnishing tumble for three days, completing the process on 19 January 2022. I could have burnished it longer but I was anxious to make the batch available for this series of Posts as it was my first batch of polished Timaru stones. Stone #21 has ended up completely smooth but definitely smaller in size than originally, being 4.5 cms long, 3 cms wide, and about 0.75 cms thick. I am very happy with the finished product.

The Index to the January 2022 Stone of the Day Series is here.

January 2022, Stone of the Day #18 – It’s Black and White!

I find black and white stones attractive, though they are not very common. This one comes from a beach near Kakanui in North Otago:

It is 4.5 cms long, 3 cms wide and just a few millimetres thick. It has polished reasonably well, with but two or three tiny holes still in it. The vein running from top to bottom on both sides adds interest. Close-up views reveal that it has experienced some stresses in its life.

Other side of Stone #18.

It might be a quartzite stone – a variety of types of quartzites are found on this beach near Kakanui (see Stone #11).

.Some scences from the south end of this Kakanui beach:

South end of Kakanui fossicking beach, looking south.
South end of Kakanui fossicking beach.
Seal in the south end rocks.

The Index to the January 2022 Stone of the Day Series is here.

January 2022, Stone of the Day #11 – Kakanui Quartzite

The beach on which I spend most of my time when fossicking near Kakanui in North Otago has many quartzite stones. Most of them are yellow in colour, some are red or with red patches, some have brown in them and some, like this one, are quite light or more neutral in colour.

These are one of my top ten favourite types of stones. I am intrigued by the patterns within them arising from how the colouring mineral is dispersed through them. An idea of the range of colours of these quartzites can be found in the entry for Wednesday 26 May 2021 in this Post (which also mentions that such quartzites are likely to originate in Central Otago).

These quartzite stones are often very smooth when found and also polish very well. I have found them at Timaru and Birdlings Flat so I suspect they can be found on other North Otago and Canterbury beaches as well, if not even further afield. Polishing clarifies the often tiny clear pieces of quartz in the stone. This one was tumbled in 400 grit then 600 grit before going into tumble polish tin oxide for 14 days and a borax burnishing tumble for three days.

The other side of Stone #11.

Stone #11 is just over 3 cms long, but much larger ones can be found at Kakanui, and I have some in my collection that are around 10-12 cms long. Below are photos of two of them that have just finished a 400 grit tumble in a 6lb barrel and of one (13 cms long) too big to tumble that sits on a shelf in my home office.

Neutral coloured Kakanui quartzite 9.5 cms long, just out of a 400 grit tumble in a 4lb barrel.
Yellow Kakanui quartzite 9 cms long, just out of a 400 grit tumble in a 4lb barrel.
Kakanui quartzite, 13 cm long, dry, too big to tumble.
Same Kakanui quartzite, 13 cm long, wet..

Most of the stones are oval and reasonably flat. The occasional one can be almost cylindrical.

Quartzite in cylindrical shape, as found on a Kakanui beach.
Yellow quartzite on a Kakanui beach.
There are also quite a few yellow-orange iron-stained quartz stones there.
Backdrop to Kakanui, June 2020.

Stone of the Day #12 is here. The Index to the January 2022 Stone of the Day Series is here.

“Q” is for “Quartzite Stone from Kakanui” and “R” is for “Riverton Rocks Red Rock”

L is for Leithfield Beach Petrified Wood
M is for Muscovite Mica from Joyce Bay
N is for November in the Calendar
O is for Opaque Orepuki Orbicular Jasper
P is for Planet in a Pebble

The following are my Posts for “Q” and “R” in the alphabetical series of a Facebook Group I belong to, “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Posts in this Series can be found here.

“Q” is for “Quartzite Stone from Kakanui” – The most common colour for this kind of quartzite in this area is yellow, though some have red in them and others, like this one, are mainly a more neutral gray. What I find fascinating with these quartzites is how small clear quartz crystals become apparent in the close-up images.

Side A.
Side B.

This stone is Stone #6 in my blog’s daily series marking the National Lockdown, one of the “projects” I work on to help keep me occupied over this period. For those interested, the Series starts here.

“R” is for “Riverton Rocks Red Rock” – This small thin flat dark-red tumble-polished stone was originally collected from one of the beaches of Riverton Rocks, the area of holiday homes that stretches south along the coast from the Southland town of Riverton/Aparima.

Located 30 kms east of Gemstone Beach (Orepuki) and 40 kms west of Invercargill, Riverton/Aparima is the oldest pakeha settlement in Southland. A whaling station was established there in the mid-1830s with land-based economic activity replacing that by the 1850s. Riverton Rocks (comprising Taramea Bay, Mitchell’s Bay and Henderson Bay – see photos below) became an important seaside holiday destination. My grandparents owned a crib (bach) at Henderson Bay from the late 1950s/early 1960s and I spent many Christmas holidays there.

Riverton Rocks. Source of base photo = http://www.stuff.co.nz/…/5058623/Riviera-of-the-south
Riverton Rocks and Back Beach. Source of base photo = http://atoz-nz.com/location/riverton
The eastern end of Taramea Bay, with Riverton town across the estuary. Source = http://www.newzealand.com/nz/plan/business/riverton-southland/
Mitchell’s Bay, Riverton Rocks. Source = https://southlandnz.com/western-southland/natural-attraction/taramea-bay-mitchells-bay?fbclid=IwAR30MlkXxdY58sdV_mCegwFvjLnnFfh2prtjunXQnzF-EFGNvjRrFF3CZEc
Henderson Bay, Riverton Rocks, my photo.

The Back Beach, at the end of the “Rocks Highway”, faces Stewart Island/Rakiura across the often-stormy Foveaux Strait, and is the best fossicking place close to and east of Gemstone Beach. My very first batch of tumble-polished stones (19 April 2016) had been collected from Riverton beaches.

The Back Beach on a stormy day.
The stones of the Back Beach.
Looking from the Back Beach towards Rakiura/Stewart Island.
My first batch of tumble-polished stones, from Riverton, 19 April 2016.

For the next Post in this Series, see here. For the Series Index, see here.

National Lockdown Number Two: Stone Six

Stone Six is a quartzite stone from Kakanui, North Otago. The most common colour for this kind of quartzite in this area is yellow, though some have red in them and others, like this one, are mainly a more neutral gray.

Side A.
Side B.

As the University of Auckland geology website states: “Quartzite is a metamorphic rock formed when quartz-rich sandstone or chert has been exposed to high temperatures and pressures. Such conditions fuse the quartz grains together forming a dense, hard, equi-granular rock.” What I find fascinating with these quartzites is how small clear quartz crystals become apparent in the close-up photos.

Stone of the Day #7 is here.

FB Group Posts: 5, 6 & 7 June 2021 – Birdlings Flat Stone, Timaru and Moeraki Village Fossicking

This is the eleventh Post in this Series of my daily Posts in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Post in this Series is here.

Saturday 5 June 2021: Tumble-polished stone found on Birdlings Flat sometime over the last couple of years.

Other side of stone.

Sunday 6 June 2021: Three finds from my time on a beach just south of Timaru this morning. I am on my way south again to restock my beach stones for tumble polishing. My very first visit to this beach was yesterday, I just had to go back today, as there are some beautiful quartzites there. I also saw three seals. Right at the end, I came across a tiny fish (about 4 cms long) gasping for breath a couple of metres up the beach from the waveline – I carefully returned it to the sea.

I found a few green quartzites.
I’m hoping I can tumble this one in my 12lb barrel.
The beach just south of Timaru. I suspect recent stormy days have piled up more stones than usual – or at least given them a big stir.
The tiny fish I returned to the sea.

Monday 7 June 2021: Five small stones from my visit this morning to a beach near Moeraki Village, North Otago. Close inspection of each revealed fascinating details. Most are chalcedony (agate). The first three stones:

Stone 1 – small agate with “fortifications”.
Stone 1 held up to the light.
Stone 2 – orbicular chalcedony?
Stone 3 – another small agate.

It was difficult to see the details of these small stones before working with the photos. On the beach, I could often just see a hint of something interesting going on. Here is a photo of the beach, followed by photos of the other two stones:

The small beach near Moeraki Village.
Stone 4 – likely also to be chalcedony of some kind, maybe dendritic.
Stone 5 – conglomerate of some kind?

See here for the next Post in this Series.

FB Group Posts: 26, 27 & 28 May 2021 – Kakanui Quartzites and Slope Point & Gemstone Beach Stones

This is the eighth in this Series reproducing my recent regular Posts in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Post in this Series is here.

Tuesday 25 May 2021: This is the day I made a Post in the Group’s Alphabetical Series – “D” is for “Dendrites” – see this Post.

Wednesday 26 May 2021: Four small quartzite stones from Kakanui, recently tumble-polished. Between 2.5 cms and 3.5 cms in size, varying colours.

Red Kakanui quartzite.

Some research over the last couple of days has led me to the following: Quartzite is usually a metamorphosed sandstone. The intense heat and pressure of metamorphism causes the quartz grains to compact and become tightly intergrown with each other, resulting in a very hard and dense quartzite – see photo of quartzite under a microscope below (from https://www.alexstrekeisen.it/english/meta/quartzite.php – the very tightly packed quartz grains in this photo range in colour from white to gray to black depending upon their optical orientation).

The stones on the beach near Kakanui where I found these four small quartzites.
Microscopic view of quartzite from http://www.alexstrekeisen.it/english/meta/quartzite.php. Very tightly packed crystals. The colour of the crystals depends on their orientation to the view.
Page 34 in Thornton’s “Gemstones” https://www.onnaturesedge.co.nz/downloads/nzgemstones.pdf
Reference to “Quartzite from Central Otago”.

Geology.com reports that quartzite is usually white to gray in colour – if stained by iron, it can be pink, red, or purple, while the presence of other minerals can cause quartzite to be yellow, orange, brown, green or blue (see https://geology.com/rocks/quartzite.shtml). In her page on beach pebbles from Moeraki-Kakanui in “Gemstones”, Jocelyn Thornton includes a “Quartzite from Central Otago”, and the photo is of a stone very similar to Stone 3 (see photos above) – see page 34 here. On page 20, “Other Varieties of Silica”, Thornton notes: “Quartz sands cemented by silica make an extremely hard and durable quartzite which is found on some hillsides in Central Otago and washed down rivers and out along the coasts. These quartzites have cloudy patterns and take a very good polish.”

Thursday 27 May 2021: Three small recently tumbled stones from a beach near Slope Point in the Catlins, Southland. 2 cms to 4 cms in size. Jocelyn Thornton writes of Slope Point: “On the Southland coast between Waipapa Point and Haldane there are a few pebbly beaches visited by fishermen and rock collectors. The cliffs contain layers of conglomerates with pebbles which weather out and collect on the beaches. At first glance they appear dark, but closer examination reveals a multitude of subtle colours and patterns” (page 35 here).

Interesting lines and patterns.
Opaque stone (not transparent).
Rhyolite.
The three small stones.
The beach just west of Slope Point, where the stones were collected.

Friday 28 May 2021: Small Gemstone Beach (Orepuki, Southland) polished stone, 3.5 cms long, collected earlier this year. Came out of a tumble barrel yesterday. Striking green lines.

Other side of stone.

[A comment on this Post from a resident of Scotland: “Love those epidote patterns, John. I am amazed that we have conglomerate cobbles from a Mississippi type delta down the Angus coast of Scotland that mirror the ones you post. These originated in Greenland/ N America poles apart”.]

The next Post in this Series is here.

FB Group Posts: 15, 16 & 17 May 2021 – Birdlings Flat “Polish Failure”, Another Birdlings Flat Quartzite, and Birdlings Flat Banded Agate

This is the fifth in this Series reproducing my recent regular Posts in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Post in this Series is here.

Saturday 15 May 2021: The failure to polish… There are two processes I enjoy – finding interesting stones, and seeing them tumble-polished. The first does not always lead to the second – sometimes a stone does not polish, or not very well. After a few years’ experience, I have a good idea which stones will polish and which will not. Then there are those stones that look really interesting but I kinda guess they may not polish. Some I try anyway – because the stone is so interesting, and I have hope. I found this stone on Birdlings Flat on 24 August 2020 and finishing polishing it two days ago. It is 3.5 cms long.

One side of the polished stone.
Closer image of the polished stone.
Other side of the polished stone.
The stone as originally found on Birdlings Flat.

It didn’t really polish, but remains fascinating and will be kept in my collection. It is volcanic, [probably andesite], would originally have had lots of holes in it, and these holes have filled with minerals as water moved through over thousands and thousands of years. Generally, the infill material polished much better than the host material.

[Comments on this Post included “Some of the infill is banded and is tiny agates… Pretty red matrix too”, “Likely originated from the Rangitata River” and “See these in the Hinds River too. Varying sizes”.]

Sunday 16 May 2021: Birdlings Flat quartzite, recently tumble-polished, 5.5 cms long, still 3 or 4 very small areas of shallow rough places on it but I didn’t want to reduce it in size any more. It is far to interesting to me in its complexity to risk losing some of that by further tumbling.

Monday 17 May 2021: Banded beach agate, Birdlings Flat, just finished tumble-polishing. Five cms long, polished to a very smooth finish. I was amazed that the small marks caused by bashing against other stones and rocks in the waves actually seem to go quite deep, were not removed by tumbling (400 grit then polish).

One side of the polished stone.
Treasure
Held up to the sunny sky.
With a torch behind it.

The next Post in this Series is here.

FB Group Posts: 12, 13 & 14 May 2021 – A Back Beach Breccia and Two Birdlings Flat Quartzites

This is the fourth in this Series reproducing my recent regular Posts in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Post in this Series is here.

Wednesday 12 May 2021: Tumble-polished stone (6.5 cms long) from the Back Beach, Riverton/Aparima. In some ways, a very ordinary looking stone. A closer look reveals complexity, subtlety, beauty. [Probably a breccia stone, made up of fragments in a fine-grained matrix.]

The Back Beach, at the end of the Rocks Highway, Riverton/Aparima. On Foveaux Strait, across from Stewart Island/Rakiura. Source: zoomin.co.nz.
The Back Beach, hit the by swells of Foveaux Strait. Great for tumbling stones the natural way!
The stones at the western end of the Back Beach.

Thursday 13 May 2021: Small Birdlings Flat quartzite, just out of the tumble-polisher this morning, collected sometime between one and two years ago. Very smooth, nice colours, 3 cms long.

Treasure

Friday 14 May 2021: Another Birdlings Flat quartzite that finished tumble polishing yesterday, 5 cms long, very smooth except for one small shallow crack along the side. I wasn’t sure what it was until I did the close-ups. Interesting iron staining.

[I added a comment to this Post: “I think the grey colour of the stone, like most of this is, is kinda the neutral base for the yellows and reds. At least, that is the thought that has been going around in my mind for a couple of years now”, and a Group Member replied: “I too have looked at them and thought it’s as though different colours, in varying degrees of coverage, have been washed over a grey base. I’ve also looked at the stones I have of that type and wondered if some of the variation was due to them being at different stages of formation or ocean tumbling…”]

The next Post in this Series is here.