Category: Beach Stones

August 2025 Stone Collecting Trip – Part 3, First Visit to Gemstone Beach, Friday 1 August

Looking back towards the Gemstone Beach carpark from the other side of the Taunoa Stream.

Today I arrived down at the Southland coast, having driven about 1,250 kilometres from home in Whanganui. I was heading to Chrissy’s place at Papatotara, just west of Tuatapere, where I am staying for the next three weeks. Gemstone Beach is on the way, so Chrissy and I met up there for a quick fossick. I arrived at the beach at 1pm, and we spent about one hour and 40 minutes hunting for stones. It was a cold but sunny day. There was a lot more sand and fewer patches of stones than usual but still lots to search. The waves were more unsettled and a little less predictable than normal, due to the recent large Russian earthquate. So we kept an eye out for any that were coming up the beach faster and further. We met Carmen and William, a local couple who are keen stone collectors and polishers. And then a wave did catch Chrissy and I near the Taunoa Stream on our way back and I got two gumboots full of freezing cold water.

Looking back towards the Gemstone Beach carpark from the other side of the Taunoa Stream.
The house in the cliff.
Chrissy fossicking, with Ohla the dog at the far right, near the cliffs.
Ohla warming up in the sun after we got to Chrissy and Mike’s place.
My 19 finds today.

I collected only 19 stones today. This was partly due to the conversations I was having with Chrissy, catching up on things. But it also takes time for my fossicking eye to develop, my last fossick down here being in March, some four months ago. The stones I most easily recognised were the trace fossil ones – the shapes seemed to stand out clearly to me. Here are three I collected. The first two are the more common colour of light-hued traces in grey-green stones, the third being an unusual set of raised dark red traces in a dark grey stone:

Trace fossil stone, Gemstone Beach.
Trace fossil stone, Gemstone Beach.
Trace fossil stone, Gemstone Beach.

For some background on trace fossil stones, see the Post “Green Argillite Stones” in the Series “Gemstone Beach and its Stones: An Introduction for the Passing Motorist”. Stones Gn40 to Gn62 there contain trace fossils, and there is accompanying information on them.

I also found these three different kinds of stones with green epidote in them. The first is the most uniform in colour and texture, the second has swirling patches of epidote plus small fragments of white quartz, and the third has areas of brighter more intense green:

The seventh featured find is a small rhyolite, a volcanic stone:

Small rhyolite, Gemstone Beach.

And the final one today is another igneous stone, this time a black and white one, I’m not sure of its identification

White spotted volcanic stone.

In the Post “Stones With White Spots & Crystals” in the Series “Gemstone Beach and its Stones: An Introduction for the Passing Motorist”, there are examples of the range of white-spotted igneous stones on Gemstone Beach – see Stones W43 to W63.

A second trip to Gemstone Beach is the subject of the next Post in this Series, “Between the Beauty and the Pain”. An Index to the Series is here.

TS2 – SLOPE POINT: THE STONES

Black Point Beach, Slope Point.
Stones, Black Point Beach.
Bach Beach, Slope Point.
Stones, Bach Beach.

Many of the stones on Slope Point beaches are different from those I have found on other South Island beaches. There is a preponderance of volcanic stones, especially rhyolites (see Thornton’s “Gemstones”, page 35 here) (see photos below). Many of the rhyolites are colourful and contain interesting patterns, such as flow-bands and orbs. One kind of rhyolite is spherulitic, also known as “chrysanthemum rhyolite”. “Flower garden” is the local name for a rhyolite with “white and grey circles and centres” (Thornton, page 35 here) (second row below, far right).

Flow-banded rhyolite.
Flow-banded rhyolite.
Rhyolite.
Rhyolite.
Chrysanthemum rhyolite. Found by Oliver Simpson.
Chrysanthemum rhyolite.
Chrysanthemum rhyolite.
“Flower garden” rhyolite.

Rhyolite has a very high silica content and is the volcanic equivalent of granite. It is formed from magma that is extruded from a volcanic vent to cool quickly on the surface rather than slowly below ground. Generally fine-grained in texture, rhyolite may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matrix. Depending on the nature of its emergence, rhyolite can also take the form of obsidian and pumice. According to John Farndon’s (2015) “Illustrated Guide to Rocks & Minerals”, spherulitic rhyolite originates in “gas pockets of volatile vapours” which develop into “balls of radiating needle-like crystals of quartz and feldspar” (page 64) . Useful online sources on rhyolite are Geology.com and Alex Strekeisen. Mindat has photos of a variety of rhyolites, including spherulitic ones.

The petrified wood found on Slope Point beaches is often black but it can also be brown or grey (see photos below, top row). It is likely to have been caused by burial from volcanic-induced land slides. Fossilised tree fern stems (punga) can also be found here (see below, bottom row), though they are not common. Some of the specimens below were found by Oliver Simpson and I tumble polished them for him. As Thornton puts it in her “Gemstones” booklet (1985), “Wood can be turned to stone when it is buried in waterlogged sediments carrying dissolved minerals which soak into the wood and replace the organic material or seal it from decay” (page 21). Interesting online material about petrified wood can be found at Rockseeker.com and Wikipedia.

Black Slope Point petrified wood.
Slope Point petrified wood.
Slope Point petrified wood.
Fossil tree fern stem, Slope Point. Faint shapes. Found by Oliver Simpson.
Fossil tree fern stem, Slope Point.
Fossil tree fern stem, Slope Point. Found by Oliver Simpson.
Fossil forest floor, Slope Point.

Another Slope Point stone is called fossil forest floor – Thornton refers to it as material preserved in silica: “stems, roots, leaves and so on” (see page 24 here). One specimen is shown immediately above, far right of second row.

Oliver once found a fossil coral stone at Slope Point (photo below, top left), maybe agatised (see this Post about a Gemstone Beach find for some information on fossil coral). Beach agates are rare on these beaches, though agate or chalcedony veins or infilled crevices can be seen in some stones. One unusual type of agate, a joon agate, can be found here but it too is rare. The final stone below, second row far right, is full of tiny unidentified fossils of some type.

Fossil coral from Slope Point. Found by Oliver Simpson.
Small beach agate, Slope Point.
Unusual Slope Point agate.
Agate veins and in-filled crevices can be found in Slope Point stones.
Slope Point stone with agate in tiny veins.
Agate in large petrified wood rock, Slope Point.
Maybe a joon agate, Slope Point.
Slope Point stone with unidentified tiny fossils.

There are a lot of breccia stones amongst my Slope Point finds. I have also found two poppy jaspers (one quite tiny) and one stone similar to Kakanui’s fossil bryozoa. A range of other more common stones occur at Slope Point as well, such as jasper, granite and quartzite.

Slope Point breccia stone.
Slope Point breccia stone.
Slope Point breccia with some rounded clasts.
Poppy jasper, Slope Point.
Slope Point stone similar to Kakanui bryozoan fossil stone.
Small Slope Point jasper.
Small granite stone, Slope Point.
Quartzite, Slope Point.

The following are the Posts on TumbleStone Blog significantly featuring these Slope Point stones:

Return to SLOPE POINT

HOME – FOSSICKING BEACHES – BEACH STONES – TUMBLE-POLISHING

March 2025 Stone Collecting Trip – Part 32, In Retrospect

This Post looks back upon my most recent stone collecting trip as presented in the preceding 31 Parts. All the photos below come from that Series, the Index to which starts here.

Ward Beach, looking back towards the carpark and campervan area, from the south.
Stones of Timaru South.
Looking towards the south end of Seadown Beach.
The last little bay I visited before turning back. Kakanui’s Seadown Beach.
Powerful waves crashing against the rocks at Slope Point.
More Slope Point stones.
More driftwood, at the high tide mark, near Waimeamea River mouth, Gemstone Beach.
Gemstone Beach stones.
My Gemstone Beach turning around point, near the Waimeamea River lagoon.
The Taunoa Stream on its way to the sea. Gemstone Beach.

I am able to drive south to collect beach stones two or three times a year, one of the benefits of retirement and reasonably good health. I usually spend three or four weeks based on the south coast, visiting Gemstone Beach, Slope Point and Riverton Aparima. On the way down and then back home again, I drop in on Kakanui and Ward Beach, sometimes Timaru and maybe another beach or two as well. I am indebted to Petra, my wife, who holds the home fort while I am away, and to Ray for allowing me to stay at his Riverton crib, making these trips possible. I am also grateful to those fellow fossickers who accompany me on the beach or who I meet there.

Horses and riders, Gemstone Beach.
Chrissy taking photos of stones, Gemstone Beach.
Paragliders over Gemstone Beach.
On the way back to the carpark. Five fossickers on Gemstone Beach.
Rich and son at the Waimeamea River mouth.
Wendy and Rudy, Gemstone Beach.
The local gold miner on his way over the Taunoa Stream, his fox terrier trotting along behind.
Me (left) with Lois and George, Club members. Photo by Andrew Thompson-Davies from his phone. Gemstone Beach.
Chrissy walking along the edge of the Waimeamea River mouth. Low enough to cross today.
Chrissy’s phone photo of me on the way down to the beach, Slope Point.

I tend to restrict myself to beaches I know well, that are likely to have stones that are interesting and that will tumble polish nicely. During this trip of 37 days, I had a total of 32 fossicks – 16 on Gemstone Beach, eight on Kakanui’s Seadown Beach, two fossicks each at Slope Point, Riverton Aparima, and Ward Beach, and one fossick each at Timaru and near Kekerengu on the Kaikoura Coast. I calculate that I spent nearly 70 hours on beaches, enjoying the environment and collecting stones.

Three Hector’s dolphins, Ward Beach.
Heron, Kakanui’s Seadown Beach.
Heron, Kakanui’s Seadown Beach.
Shag, Waimeamea River lagoon, Gemstone Beach.
Gull group on Gemstone Beach.
Ohla the dog. Gemstone Beach.
Chrissy’s phone photo of the sea lion that was located half way up the track, in long grass near a large flax bush. Slope Point.
Hector’s dolphins, Back Beach, Riverton Aparima.
Ohla having a sitdown next to me. Gemstone Beach.
The insects on the rock, Kakanui’s Seadown Beach.

On these beaches, I always stumble across stones that surprise me with their beauty, their intricate patterns, and the amazing sights that are revealed by close-up photos. The highlights of this visit include the following finds. Links are made to the Posts in which the stones feature. It’s difficult to select the highlights as every stone I collect has caught my eye on the beach. I’ve managed to whittle it down to the 65 stones featured below.

The find I most value from this trip is a very small orbicular jasper from Gemstone Beach – the first time I have found such a stone with tiny white orbs:

Small orbicular jasper with tiny white orbs.
Other side of stone.

Among the other surprising and delightful finds were some very small dark red jaspers, their beauty fully revealed only by the photos. This one is from Slope Point:

Fragment of a jasper.

This one is from Gemstone Beach:

Tiny jasper.
Another side of tiny jasper.

From Kakanui:

Small jasper.

Another from Gemstone Beach:

Again, Gemstone Beach:

Finally, also found on Gemstone Beach:

I am attracted to stones with a lot of detail within them. I really like the patterns in these two very similar Gemstone Beach stones:

A kind of similar type of pattern in a stone from Slope Point, but a very different colour:

Perhaps the most interesting veined stone I found is this one from Gemstone Beach:

A colourful stone from Slope Point:

Slope Point beauty.

Another colourful Slope Point stone, a sedimentary one:

An unusual stone with bright white in it, from Gemstone Beach:

Another interesting patchy white stone, this one a breccia from Slope Point:

This interesting patterned and very smooth stone is from Gemstone Beach:

A specimen of the intriguing bryozoa fossil stone from Kakanui:

Bryozoan fossil stone.

And a similar stone from Slope Point, found there for the first time in my experience:

Very similar to a Kakanui bryozoan fossil stone.

This Gemstone Beach find has a really interesting pattern in it, and it might be a hydrogrossular garnet:

During the same fossick, I found this stone, the most impressive of the many breccia I found:

A mudstone that was crushed then flooded with green epidote.

Maybe the best of the other breccias with epidote in them, also from Gemstone Beach:

Though this light green breccia from Gemstone Beach is also very attractive:

Epidote in a type of quartzite from Kakanui:

And a small very intense green stone from Gemstone Beach:

From Kakanui, an unusual colour – dark brown – of a kind of quartzite found there which usually comes in yellow or light-grey:

Quartzite?

Another unusual Kakanui quartzite, with breccia-like “spots”:

At Kakanui, I always look out for limestone pebbles with fossils in them – this one is a great example of the type:

Fossiliferous limestone.

A small Ward Beach speckly stone that turned out to contain tiny regular-sided crystals:

Small sparkly stone.

A Slope Point stone with lots of different things in it:

A type of iron-stained quartz with spectacular patterns, from Gemstone Beach:

A smaller quartz, again from Gemstone Beach, more sugary but with a similar range of hues:

And a variation on the same theme from the same beach – quartz and brown hues:

A Gemstone Beach find that I really liked, though the photo fails to do it justice:

From the Beach Past the Back Beach at Riverton Aparima:

The most interesting argillite stone I found on Gemstone Beach:

The most unusual pink-type stone I collected, found on Gemstone Beach:

Gemstone Beach’s poppy jaspers are always a delight to find – here are six collected on this trip:

I am always excited to find petrified wood. At the start of my fossicking career, it was the main type of stone I wanted to find. This trip, I found the following pieces on (in chronological order) Slope Point, Gemstone Beach, Slope Point, Kakanui and Kakanui:

Slope Point petrified wood.
Petrified wood, wet, Gemstone Beach.
Another side of the pebble.
Petrified wood, wet.
Wet petrified wood stone.

Among the trace fossils in argillite stones collected from Gemstone Beach were these (the third one below was given to me by Lee Gibbs, and Chrissy also often gives me trace fossil stones she finds while in my company):

Trace fossils in argillite.
Trace fossils in argillite.
The gorgeous trace fossil stone that Lee kindly gave me.

And two of the larger trace fossils in limestone found on Ward Beach:

The two most interesting beach agates I found this trip, from Slope Point and Kakanui:

Agate, Slope Point.

A stone with a glassy green character, maybe chromite in quartz, found on Gemstone Beach:

And, finally, five of the hydrogrossular garnets from Gemstone Beach:

Hydrogrossular garnet.
Hydrogrossular garnet.

The tumble polishing begins…

I collected about 70 stones today.
Today’s collection of finds.
My 90 finds from Slope Point today.
My 50 finds today.
Today’s finds.
85 of my Slope Point finds.
My finds from Gemstone Beach today.
My Gemstone Beach finds today.
This morning’s finds, Kakanui.
My Kakanui finds this afternoon.
My finds from this fossick, Kakanui.
My Ward Beach finds.

An Index to this Series starts here.

March 2025 Stone Collecting Trip – Part 1, Ward Beach and Hector’s Dolphins, Thursday 27 February

Ward Beach, looking back towards the carpark and campervan area, from the south.
Three Hector’s dolphins, Ward Beach.
The 30 stones I collected today.
Small sparkly stone.
Side B of small hematite jasper.

My March 2025 trip actually began at the end of February with this visit to Ward Beach in Marlborough. This was the first day of a five week trip to the South Island to collect beach stones for tumble polishing. I left home in Whanganui the day before to catch a Cook Strait ferry in Wellington. After reaching Picton in the South Island, I drove for an hour to Ward, arriving at the Flaxbourne Motel in the early evening yesterday. This morning, after checking-out, I drove to Ward Beach. The weather was warm and partly cloudy.

Ward Beach, looking south from the carpark.
Ward Beach, looking north from the carpark.
Ward Beach, looking back towards the carpark and campervan area, from the south.
The 30 stones I collected today.

At this time of year, in late summer, there were quite a few campervans in the camping area behind the carpark. A small number of people were on the beach, exploring it. One man with binoculars mentioned that he had been watching some dolphins for an hour or so. I had just noticed them and spent some time trying to get some decent photos of them. But that was a difficult task. These were Hector’s dolphins, the smallest of all the dolphins, identifiable by their rounded dorsal fin (similar to the shape of Mickey Mouse’s ear). See Wikipedia for more information on them.

The “Mickey Mouse ear” shape of the dorsal fin of the Hector’s dolphin.
Closer view of the previous photo.
They came quite close to the shore.
Three Hector’s dolphins, Ward Beach.
There were six to eight dolphins in the bay.
A view from the side, when I was further south on the beach.

I eventually tore myself away from dolphin watching and walked south towards the Flaxbourne River mouth looking for stones. The river flow was very low – it has been a dry summer, and a bank of stones has blocked off the mouth (though no doubt some water will be seeping through the stones to the sea).

A person stands on a bank of stones where the Flaxbourne River usually flows to the sea.
The river ponded behind the stones, but maybe seeping out through the stones to the sea.
Very low flow in the Flaxbourne River.

Conditions were not very good for finding interesting stones – the waves were wetting sand rather than stones this morning. I collected about 30 pebbles today, mainly jaspers and limestone and flint, with some trace fossils. For an indication of the range of types of stones that can be found on Ward Beach, see the Series “Selection of Tumbled Ward Beach Stones” that begins with Part 1 on trace fossils. Below, I feature eight of today’s finds.

Photos can be revealing. I picked up the first stone (below) because it sparkled. However the photo and close-up show that the sparkles are tiny square or rectangular crystals, I thought they would have been circular – fascinating! The second stone is mainly flint – the dark colour – and only upon doing the close-up photos did I notice the chalcedony/agate in the vein.

Small sparkly stone.
Chalcedony/agate vein in flint?

I continued to keep an eye out for jaspers, a kind of stone I had largely ignored on this beach until last year. The most interesting (colourful) had hematite and quartz in it.

Side A of small hematite jasper.
Side B of small hematite jasper.

Two other jaspers I collected:

There are more limestone stones on Ward Beach than any other types. Some are colourful and are brecciated, often with white veins, as the first one below. Others are light grey with trace fossils in them.

Limestone is too soft to tumble polish normally. However, a short tumble of a handful of days in fine grit removes the cloudy surface and leaves a nice smooth waxy-feeling stone. The waxy feel is unusual and distinctive. Tumbling doesn’t give such a stone a high polish, but its surface is permanently clear, showing any trace fossils well. For more on the Ward Beach trace fossils, see “W is for Ward Beach Zoophycos”.

Next beach stop, Timaru. See here for the next Post in this Series.

September 2024 Stone Collecting Trip –Part 8, Southland Geological and Lapidary Club, Thursday 12 September

Facebook Page. http://www.facebook.com/profile.php?id=61550961891487
Website. http://www.sglc.rocks/
Kakanui bryozoan fossils.
Kakanui agatised bone(?)
https://tumblestoneblog.wordpress.com/2019/06/30/the-elusive-sapphire-of-gemstone-beach/

The Southland Geological and Lapidary Club was re-formed recently, after an eight year recess. Its website is here and its Facebook Page is here. I joined in order to support it and with the hope of going along to a meeting when I am down south on a stone collecting trip. Club meetings, which are open to everyone, are at 7pm on the second Thursday of each month at the Seminar Room at First Presbyterian Church in Invercargill. This month’s meeting coincided with my current trip so I emailed the Secretary, Tina, to let her know I would be attending. She replied, asking if I would say a few words about myself and my TumbleStone Blog at the meeting. So on Thursday night I drove the 40 minutes from Riverton to Invercargill in the company of Chrissy, author of Tumble and Polish. We sometimes fossick together, especially on Gemstone Beach. See this Post about a Te Waewae Bay fossick we did. It was also Chrissy’s first Club meeting.

There were 11 of us who gathered on a cool Southland night. A number of people brought along recent finds or other interesting stones, including some ventifacts, as well as some nicely-polished stones. It was good to meet Tina, the person behind the Club’s emails to members. She explained to the group that this was going to be an informal session. I had scribbled down a page of notes to try to get my thoughts in order – it’s been a while since I have done any public speaking and I wasn’t sure how things would work out. I started by mentioning my links to Southland, despite the fact that I now live in Whanganui. I had actually read my About Me page on TumbleStoneTwo prior to the meeting, which helped me to organise a brief biography. I noted my time as a university lecturer, which explains how I approach many of my blog posts which are basically reporting on research I do about stones and tumble polishing. I explained why I started TumbleStone Blog – because I couldn’t initially find any New Zealand-based internet material on stone collecting and tumble polishing. I noted that I collect mainly very smooth beach stones – they’re easier to polish – and went through the main beaches I visit in the South Island. I described my approach to taking photos of stones and preparing images for the blog – using a digital camera, with the stones in bright sunshine, taking large images so they can be cropped to show a stone’s detail.

The polished Kakanui stones I took along.
The polished Slope Point stones I took along.
The polished Gemstone Beach stones I took along.

It was an informal session – people asked questions and made comments as we went along. I had brought along some of my polished stones from Kakanui, Slope Point and Gemstone Beach (see photos above). At times I picked out a stone and talked about it, such as the fossil coral I found on Gemstone Beach and the bryozoan fossil stones from Kakanui’s Seadown Beach. I also showed my recent Kakanui find of what could be an agatised fossil bone piece. Gemstone Beach’s hydrogrossular garnets were mentioned a couple of times, and I noted that my blog has a post on variations of that stone, based largely on “local knowledge” from a number of sources. I picked out a banded ignimbrite from Gemstone Beach and explained how it had come to be identified for me as this kind of rhyolite. I talked about my fascination with petrified wood and the large piece I found at Slope Point last year. Jack Geerlings was at the meeting and I was pleased to make his reacquaintance. I had met him briefly on Gemstone Beach in 2019 and later visited his amazing stone collection in Winton. He had shown me his Gemstone Beach sapphires which feature in one of my most-read blog posts, “The ‘Elusive Sapphire’ of Gemstone Beach”. After my talk, I was able to chat with a number of Club members, though didn’t manage to get around everyone. I hope everyone enjoyed the evening as much as I did.

Part 9 features three stones from relatively brief visits to three beaches. The first Post in this Series can be found here.

Early 2024 Fossicking Trip – Part 34, Final Fossick of the Trip, Ward Beach, Monday 25 March

This afternoon, after driving from Christchurch, I spent just over an hour at Ward Beach. This area of the coast was raised by the 2016 Kaikoura Earthquake. I searched for interesting stones along a 300 metre stretch of the beach in front of the carpark.

Looking back at the carpark (my red car there), camping area in background, jagged limestone rocks in foreground raised by the 2016 earthquake.
Ward Beach in front of the carpark.
Ward Beach stones.
The beach to the south of the carpark.

I also ventured onto the rocks at the south end, where the Flaxbourne River mouth usually is – the river is very low and appears to have ceased flowing. These rocks have been recently uplifted and appear to be limestone with darker flint patches and nodules.

The jagged uplifted rocks at the south end of the beach.
Looking down at where the Flaxbourne River usually flows out to the sea.

Usually I am interested in, firstly, the trace fossil limestone pebbles, such as these I found today:

Trace fossil layers.
Fossil traces?

And I always look out for the patterned and pastel-coloured limestones with white veins that are common here.

Limestone pebble with intriguing veins.
Dry red limestone pebble with criss-crossing veins.
The same red limestone pebble, wet.
I think a brecciated limestone-with-flint stone.
Small limestone pebble with white vein and dark red flint at right edge.
Dark limestone pebble with markings?
Limestone pebble with horizontal markings.

But for this fossick, I also deliberately looked for stones that I normally don’t focus on. Below are six types of stones that I usually don’t find at Ward Beach, maybe because I don’t look for them:

Interesting intense dark orange mineral.
The dark yellow caught my eye, the dark red veins are a bonus, some brecciation becomes apparent in close-ups.
A jasper of this quality is unusual in my experience of Ward Beach.
Perhaps brecciated flint, with chalcedony in matix.

Saying goodbye to Ward Beach brought the end to my visits to beaches during this trip to the South Island which lasted just over five weeks. Altogether, I undertook 34 fossicks for tumblestones, the vast majority (24 fossicks) at Gemstone Beach and the nearby Te Waewae Bay coast. I caught a ferry across Cook Strait the next day and made it home to Whanganui later in the afternoon.

The Series Index can be found here.

Early 2024 Fossicking Trip – Part 33, Diverse Finds at Kakanui’s Seadown Beach, Sunday 24 March

Before I left Kakanui today on my way north, I spent two hours on Seadown Beach. Again, a good patch of stones could be found at low tide at the south end. I also walked north maybe 800 metres but the beach there had very few stones to offer. It was apparent that erosion at the back of this stretch was still continuing, and parts of the now-closed Beach Road were eroding onto the sand (see photo below). In a previous Post, written last year on Seadown Beach, I had noted that between 1957 and 2002, the average rate of erosion along Beach Road had been about 50 cm per year (see Section 5.3 of “Planning on a Retreating Coastline: Oamaru, North Otago, New Zealand”, a 2009 GNS Report).

About 800 metres north of the Seadown Beach parking area, looking south. Very few stones.
At the back of the beach is the old Beach Road, no longer open, still crumbling away.
Two Variable Oyster-catchers (Tōrea pango) on the beach. For species info, see https://nzbirdsonline.org.nz/species/variable-oystercatcher
My parting view of the south end of Seadown Beach.

Among the few stones on the stretch of beach north of the carpark was this large one with bryozoan fossils:

Side A of stone.
Side B of stone.

For more information on bryozoan fossils and this kind of stone on Seadown Beach, see Part 32 of this Series.

I have found a small number of pieces of petrified wood previously on this beach (see this Post), and this morning came across a nice specimen at the south end:

Petrified wood. Side A.
Side B.

A small piece of chalcedony (beach agate) with an interesting dark patch on one side:

One side of small beach agate.
Another side of small beach agate.

Five of this morning’s finds with interesting patterns/detail:

Yellow-orange mineral in patches, maybe white chalcedony.
A type of quartzite, with tiny chips of clear quartz?
Jasper with hematite.
Mossy-type jasper.
Jasper and quartz?

Five of the quartzites I found:

Finally, four softer stones with tiny shells in them, what I call fossilised seafloor:

This afternoon I drove to Banks Peninsula, near Christchurch, where I stayed overnight with Tracey and Ashley. Tomorrow I drive to Ward in Marlborough, and fossick at Ward Beach in the afternoon. The day after that, I am scheduled for a ferry crossing of Cook Strait followed by a drive home to Whanganui.

The next Part of this Series describes a fossick at Ward Beach, the last of this trip. The Series Index is here.

Early 2024 Fossicking Trip – Part 32, Bryozoan Fossils in Chalcedony, Kakanui’s Seadown Beach, Saturday 23 March

On Thursday, two days ago, I had my final Gemstone Beach fossick for this trip. Friday was spent packing up and driving to North Otago, a trip of more than four hours. I arrived in Kakanui, a few kilometres south of Oamaru, just before dark, staying at a holiday home booked through AirBnB. This morning, I spent two hours at Seadown Beach, a couple of kilometres north of Kakanui village. I had called in at this beach on 16 February, on my way south.

It was a very foggy morning though the sun eventually came out. Previously, a lot of sand had been covering most of the stones here. There’s still a lot of sand but the sea has removed a depth of about two metres of it across the south end of the beach, leaving a small cliff stretching for about 50 metres there. The removal of this sand has exposed a 100 metres stretch of stones close to the waves.

Seadown Beach this morning, as viewed from the roadside parking area.
The 2 metre high cliff in the sand at the south end of the beach.
Lots of stones at the south end of the beach, at low tide, by the rocks.
Seadown Beach stones, Kakanui.

The type of stone I keep the sharpest eye out for on this beach is one I first discovered in mid-2022 (see here, last part of Post). It is a dark brown colour, similar to the limonite prase found along the North Otago coast. Jocelyn Thornton describes limonite prase as an “ochre-yellow jasper” (page 34 in “Gemstones”). Two examples of limonite prase:

Limonite prase, found at Kakanui’s Seadown Beach in June 2022.
Limonite prase, found at Kakanui’s Seadown Beach in March 2024.

In June 2022, I had found a stone at Seadown Beach that reminded me of limonite prase, was a dark brown colour but did not have the typical black patches. Looking at it more closely, I noticed some very faint tiny markings in the stone. Taking a photo of it later, I zoomed in on the markings and discovered a wonderland of tiny figures:

Found in June 2022.

I posted these photos on the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. John Taylor, an Englishman who lives in Scotland but often visits New Zealand and is a member of the Group, commented that he had found a very similar rock in Europe, a “Danish Fossil Okkergelber Hornstein”. He pointed out that this rock is chalcedony and contains many tiny bryozoan fossils. When John visited me in 2023, he gave me a slice of a rock he had found at Waabs in northern Germany, just south of the Danish border, on the shores of the Baltic Sea:

Slice given to me by John Taylor.
The Waabs area on the Baltic Sea coast, Germany. Source: google Maps.
Waabs’ location in far north of Germany. Source: https://en.wikipedia.org/wiki/Waabs
A beach near Waabs. Source: https://www.meerart.de/die-straende-von-waabs

I took photos of John’s slice, wet and in bright sunlight – the tiny bryozoan fossils can be seen in the close-ups:

Side A of slice.
Side A, close-up 1.
Side A, close-up 2.
Side B of slice.
Side B, close-up 1.
Side B, close-up 2.

I have since found more of these stones on Seadown Beach. Three from visits in 2023:

Found in January 2023.
Found in May 2023.
Also found in May 2023.

The following is what I have found from some initial research into bryozoa (the term “bryozoans” is also used). In her book “The Field Guide to New Zealand Geology” (2003), Jocelyn Thornton describes bryozoans as one-celled animals (zooids) which live in colonies (page 52). Most marine bryozoans have a partially calcified, hard, body wall, which is subject to the process of fossilisation. There are many species and many different types, including branching twig-like forms, lacy forms and fan-like forms. A 2022 news article notes they are often known as “moss animals”, because the bushy-looking live ones look like moss, the literal meaning of bryozoa from the Greek, bryon meaning moss, zoön meaning animal. They are also known as “sea mats” or “lace coral”, depending on the variety and the form they take. The excellent NIWA identification guide, “Bountiful Bryozoans”, available free online, refers to individual zooids as ranging in size from 0.3 to 1.5 millimetres long, only just able to be seen with the naked eye “if you look very carefully”. New Zealander Dennis Gordon is a world authority on bryozoa and co-author of a field identification guide. In a 2003 “New Zealand Geographic” article entitled “Living Lace”, he notes  that 960 of the 1500 living species of bryozoa occur in the New Zealand region, the highest regional “bryodiversity” in the world.

Worldwide, there are about 15,000 named fossil species. According to Wikipedia, mineralized skeletons of bryozoans first appear in rocks from the Early Ordovician period (470 to 485 million years ago). The website “Fossil Finds in New Zealand” includes images showing the different forms that fossil bryozoa may take (see first photo below). Gordon reports an abundance of bryozoan fossils in New Zealand limestone: “It has been estimated that Te Kuiti limestones, including those in the Waitomo area, are 50 to 80 per cent bryozoan remains, and Oamaru stone 70 per cent.” The second photo below is of a sample of Oamaru limestone. Ernst Haeckel’s drawing of bryozoa skeletons, published in 1904, are dramatic renderings of their tiny appearance (see third photo below). He also produced a drawing of live bryozoa (Plate #23 in his “Art Forms in Nature”, published 1899 – fourth photo below).

Different forms that fossil bryozoa may take. Source: https://fossilfindsnz.weebly.com/bryozoa.html
Oamaru limestone, compressed 35 millions year old bryozoa. Source: https://www.nzgeo.com/stories/living-lace
Drawing of skeletons of bryozoa colonies and individuals by Ernst Haeckel, 1904. Source: https://commons.wikimedia.org/wiki/File:Haeckel_Bryozoa_33.jpg
Ernst Haeckel’s 1899 drawing of live bryozoa. Source: https://splendidartprints.pixels.com/featured/bryozoa-ernst-haeckel.html

Haeckel (16 February 1834 – 9 August 1919) was an influential German zoologist, naturalist, and artist, who discovered, described and named thousands of new animal species (he is also controversial due to some of his political and racial views). Haeckel’s published artwork includes over 100 detailed, multi-colour illustrations of animals. Modern scanning electron pictographs of bryozoa fossils provide a similar close-up view of their tiny skeletons.

Scanning electron micrograph of recently named NZ bryozoan. Source: https://bryozoanlableed.wordpress.com/2020/12/17/star-wars-and-a-newly-named-kiwi-bryozoan
Scanning electron micrograph of bryozoan colonies showing skeletal detail of individual. Source: http://www.nzgeo.com/stories/living-lace
Scanning electron micrograph of bryozoan colonies showing skeletal detail of individual. Source: http://www.nzgeo.com/stories/living-lace

I have yet to look more carefully at the tiny figures in the Seadown Beach stones I have found, to see how they match up with different varieties of bryozoa. And there may be other types of tiny fossils in them. I have also yet to confirm whether the stones are chalcedony or not.

To return to my visit to Seadown Beach today. I found two stones that clearly are the same as my previous finds and very similar to John Tayor’s slice:

Two other finds are less clear. They are similar in colour and both have tiny forms in them, but the forms may not be bryozoa:

The tiny forms in this stone may be bryozoa??
Not sure that this stone contains bryozoa.

Six other finds from this morning of a roughly similar colour but they are either limonite prase or yellow-brown stones of different compositions but no bryozoa:

Limonitte prase.
Limonite prase, with an interesting central patch mosaic.
This stone also has a kinf of mosaic patch to the left.
A kind of breccia?
The vein may be chalcedony?
I picked this up, thinking it might be a quartzite.

Among the other interesting stones I found today was a piece of seam agate.

Held up to the sky.
With a torch behind it.
Other side of seam agate.

In March 2021, I found a piece of seam agate a few kilometres south near Moeraki Village – see the second half of the Day 20 entry in this Post.

Other finds this morning included a number of quartzites, reasonably common on this beach:

Side A of light-coloured quartzite with intriguing clouds..
Side B of same stone.
Light-coloured quartzite with tiny clear quartz inclusions.
Quartzite with a range of hues.
A draping quartzite??
Quartzite with an intense brown mineral.
Veined quartzite.
A differently-veined quartzite.

My final five finds today follow. The last two are too soft and crumbly to tumble-polish but are specimens of Kakanui Mineral Breccia. As one source notes: “The Kakanui Mineral Breccia is a mineral-rich fragmental rock which formed from the contact of an intruding magma with water about 31.6 million years ago (Early Oligocene). The resulting violent eruption totally disrupted the magma components into angular fragments.” There is international geological interest in the breccia for a variety of reasons. More information on Kakanui Mineral Breccia can be found in this Post, about halfway through, in the section on Kakanui Beach.

Interesting mix of breccia and crystals. Side A of small stone.
Side B of stone.
Fossilised sea floor stone.
Another fossilised sea floor stone.
Kakanui mineral breccia with maybe some white chalcedony in it.
Anther Kakanui mineral breccia stone.

The next Part of this Series reports on my last fossick at Kakanui for this trip. The Series Index is here.

Early 2024 Fossicking Trip – Part 31, Farewell Fossick on Gemstone Beach, Thursday 21 March

I arrived at a crowded Gemstone Beach carpark just after noon, about an hour after high tide. It was a warm day, being around 19 to 20 degrees right up until I left at 4 pm. The big surprise walking down to the beach was to see that all the seaweed piled up there yesterday was now completely gone!

Where the seaweed had piled up yesterday.
Looking westwards from in front of the carpark, towards the Taunoa Stream.

I walked my usual fossick trail, down to the Waimeamea River lagoon. I found three or four nice little jaspers along the lagoon’s edge, and a few more elsewhere on the beach. This was one of them:

Side A.
Side B.

Four other small red jaspers I found this afternoon:

Among the green stones I found was this breccia with dark markings in the matrix:

Six other green (probably epidote) stones, including two trace fossil ones:

Green epidote and white quartz veins.
Argillite with unusual long thin trace fossil.
Another unusual colour for a trace fossil.

Finally, five more finds:

Side A of a oink-patched stone.
Side B of stone.
Fine dark red traces of mineral.
This one is a sugar-type quartz – the veins caught my eye.
I have not seen many dark quartzites like this in the Gemstone Beach area.
The light-coloured veins in this quirky little stone caught my eye.

In general, I came across very few hydrogrossular garnets this afternoon but quite a few trace fossil stones.

On my way back to the carpark, I stopped and chatted to the local gold miner who daily visits in his ATV. He often pulls a trailer behind, with a small sluice box to run water over sand to collect fine gold. His claim covers a number of kilometres of the Te Waewae Bay coast. He said that when gold mining was initially carried out here, in the late 19th century, each claim consisted of only a 12 foot (3.5 metres) wide piece of the beach – much richer ground than today! See here for a 1993 “New Zealand Geographic” article on gold mining in the Orepuki area that mentions the fine gold that can be found on the local beaches.

And it’s farewell to Gemstone Beach from me for this fossicking trip.

The next Part of this Series reports on a fossick at Kakanui as I travel north, back to Whanganui – it includes a significant section about the stones with bryozoan fossils that I find there. The Series Index is here.

Early 2024 Fossicking Trip – Part 30, Penultimate Fossick at a Seaweed Strewn Gemstone Beach, Wednesday 20 March

Today I made my second last visit this trip to Gemstone Beach. The weather was fine and warmish, 14 degrees when I arrived at 11.40am, climbing to 17 degrees when I left three hours later. There were quite a lot of other people there, the carpark was crowded. I noticed three or four surfers in the water, unusual for here, but I received a more significant surprise when I saw big piles of seaweed in front of the carpark, in places over a metre high! It thinned out as I walked towards the Taunoa Stream before thickening again at the stream. It seems to be very similar to the seaweed that has recently washed up on some Auckland beaches.

The seaweed in front of the Gemstone Beach carpark.
The man is standing in the Taunoa Stream.
Stones and sand were all mixed in with, and on top of, the seaweed.

After I crossed the stream, I found the seaweed was absent altogether after about 200 metres. I was able to make it right down to the mouth of the Waimeamea River today, at the far end of the lagoon. This was because the outlet at the start of the lagoon was only a trickle – the sea had thrown up a lot of stones, nearly blocking it off completely again.

The lagoon today. The outlet across the stones was nearly blocked.
The small flow from the lagoon outlet.
Horses on the horizon, just above the river mouth.

One of today’s finds was a pink and black stone, reminiscent of rhodonite. I found it near the end of my fossick while I was walking over the dry stones. The pink is sometimes intense and in interesting patterns:

Side A.
Side B.

This jasper-quartz stone has some nice red, purple, pink and white sections:

Side A.
Side B.

Two stones that I think could be amygdaloidal:

A couple of small black and white stones:

Six more of today’s interesting finds:

Orbicular-looking crystals?
A range of interesting details can be seen in this stone.
The very fine green mineral splashes caught my eye.
Quartzite with green epidote??
Tiny elongated crystals in here.
A kind of sugar quartz.

Part 31 of this Series reports on my final fossick, for this trip, at Gemstone Beach. The Series Index is here.