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“TUMBLESTONETWO” [Under Construction]

INFORMATION ABOUT STONES, BEACH STONE GATHERING, AND TUMBLE-POLISHING, FROM NEW ZEALAND

Amygdaloidal volcanic stone, Gemstone Beach.

Orbicular jasper, Gemstone Beach.

Banded beach agate, Birdlings Flat.

Fossil sea floor stone, Seadown Beach, Kakanui.

Quartzite, Timaru South.

Hydrogrossular garnet, Gemstone Beach.

Note – Scroll down past this Post to see the most recent Posts from TumbleStone Blog, such as: Index to “Early 2024 Fossicking Trip” Series, November 2023 Polished Stones: Stone of the Day #1, TumbleStone Calendar 2024, Gemstone Beach and its Stones: An Introduction for the Passing Motorist – Part One, Location and Carpark, An Annotated Index of Indexes on TumbleStone Blog To Date, Two 2017 TumbleStone Posts Revisited: Callanish Standing Stones, Scotland, and Malham Cove, England, and Online Access to “Gemstones” by Jocelyn Thornton (1985) .

“TumbleStoneTwo” is a website within a blog, “TumbleStone Blog”. The website’s home page is always the first post when someone goes onto the blog. Links are then made from there to other blog posts masquerading as website pages. The titles of these website pages start with “TS2” and have the TumbleStoneTwo banner at the top.

TumbleStoneTwo is a Companion Site to TumbleStone Blog but presents information in a more systematic way. Author: John Paterson, Whanganui, New Zealand, email john.tumblestone@gmail.com

THIS SITE IS STILL UNDER CONSTRUCTION. Pages will be added from time to time. Pages will also be up-dated or expanded. See LIST OF CONTENTS TO DATE for information on which Pages are “live”.

Rhyolite, Slope Point.

Brecciated hematite jasper, Gemstone Beach.

Quartzite, Seadown Beach, Kakanui.

Fossil coral, Gemstone Beach.

Trace fossil stone, argillite, Gemstone Beach.

Petrified wood, Leithfield Beach.

The information on this website is based on the firsthand experiences and research of John Paterson, a retired academic in New Zealand. I have been collecting beach stones and tumble-polishing them since March 2016, which was also when I started TumbleStone Blog.

Note that the coverage of this website is very limited. Only a few beaches in the South Island are included, because of my familiarity with them. Beaches on the West Coast of the South Island, in the Nelson region, and in the North Island, are not included. Only the stones I have familiarity with will be covered, and it is the rotary tumble-polishing method that is featured.

By early 2022, my Blog had grown too large for people to find easily some of the more useful information in it. And so TumbleStoneTwo, a new website, was born, initially to provide links to Blog Posts within a more accessible website-like framework. New information too will appear on TumbleStoneTwo.

Quartz, Gemstone Beach.

Hematite jasper, Birdlings Flat.

Unknown, Gemstone Beach.

Thulite, Gemstone Beach.

Hydrogrossular garnet, Gemstone Beach.

Quartzite, Seadown Beach, Kakanui.

My approach to beach localities and fossicking is similar to that of four books I am familiar with. The first is Bill Myatt’s (1972) “Australian and New Zealand Gemstones: How and Where to Find Them”. Pages 431 to 445 of Myatt’s book consist of a New Zealand section written by Mrs A. Niethe, detailing fossicking places in the different regions. Information is also provided about transport links and accommodation. The second book is Natalie Fernandez’s (1981) “The New Zealand Rockhound”. Her “Locations” chapter (pages 91-122) lists a multitude of places and the main types of stones to be found there.

The third book is Jocelyn Thornton’s (1985) “Gemstones”. This includes sections on seven beach areas, with photos of stones of interest to the stone polisher (accessible online here). Finally, James Crampton and Maianna Terezow’s (2010) book, “The Kiwi Fossil Hunter’s Handbook”, though about fossils rather than stones in general, has 27 chapters on localities for fossil hunting in New Zealand. They provide an excellent set of information for each locality, its geographical and geological contexts, and its fossils. TumbleStoneTwo aims to provide useful information for fossickers about a small number of New Zealand beaches and their stones.

Agate, Ward Beach.

Unknown, Gemstone Beach.

Banded argillite, Gemstone Beach.

Quartzite, Birdlings Flat.

Beach agate, Seadown Beach, Kakanui.

Moss jasper, Seadown Beach, Kakanui.

There are three Main Sections to the TumbleStoneTwo website:

FOSSICKING BEACHES – BEACH STONES – TUMBLE-POLISHING

Three supplementary Main Pages are:

LIST OF CONTENTS TO DATE – ABOUT ME – HALL OF FAME

Scratches and Rough Patches, Beauty and Wonder – Thirty Small Polished Stones from Gemstone Beach/Te Waewae Bay: Part 5, Stones 21 to 25

Gemstone Beach.

Gemstone Beach, looking northwest.

Stones on Gemstone Beach.

Stones 1 to 10, the larger ones.

Stones 11 to 20.

Stones 21 to 30, the smaller ones.

Relative size of Stones 1 and 30. $2 coin is 2.8cm across.

In this Series of Posts, 30 recently polished stones are examined – they were found on the coastline that runs north from Gemstone Beach near Orepuki in Southland, New Zealand. Many interesting and beautiful stones can be found here, brought down from the mountains of Fiordland by the Waiau River. This Series also illustrates some of the challenges a tumble polisher faces to obtain a completely smooth and well-polished stone. Part 1 in this Series of Posts described Stones 1 to 5, with the following Parts dealing with another five stones each. The five stones featured here are smaller than the first 20 and getting good clear photos of them can sometimes be more difficult as a result.

Stone 21 is a light green argillite with tiny lighter-coloured trace fossils in it. Locals often refer to these as “fossil worm cast” stones.

Stone 21, Side A

Stone 21, Side B

This Post provide some details on argillite, a hardened mudstone. Argillite stones with trace fossils in them are reasonably common on and near Gemstone Beach (and can be found elsewhere in New Zealand as well). Trace fossils are not fossils of an animal itself but of something they have left behind them, like burrows or tracks. Stones Gn40 to Gn62 in this Post are interesting examples of trace fossil argillite stones and their diversity. A small trace fossil stone is in the TumbleStone Hall of Fame. Returning to Stone 21, the bottom half of the stone has markings on it that may not be trace fossils in the usual sense but be ripples in the sediment from sea currents or from a fish swimming by.

The process of tumble-polishing does not always lead to argillite stones with a high polish. However, it removes the dull weathered surface so that things like trace fossils can be clearly seen, even when the stone is dry. I tend to tumble trace fossil stones in 400 grit, followed occasionally with a 600 grit tumble, then the polish stage. Skipping the use of the coarser grits helps to preserve the trace fossils as they appear on the surface, though some small holes and scratches may remain.

Stone 22 is a small jasper (I think) of lively brown colour, with an interesting milky quartz vein and a few very thin transparent veins.

Stone 22, Side A

Stone 22, Side B

There appear to be inclusions of quartz and maybe mica which interrupt a smooth surface. The largest vein also has some holes in it, as can be seen especially on Side A. To remove these using tumbling would have made the stone very small – it is currently just under 2 cms at its widest – with no guarantee that all the “imperfections” would be absent.

A remarkable little pebble, Stone 23 contains a small vein with tiny brecciations filling it. It’s like a glimpse into a hidden shrunken world.

Stone 23, Side A

Stone 23, Side B

As noted in relation to Stone 1, breccia are angular fragments of stone that have been compressed together in a fine-grained matrix. There are a number of different causes for brecciation, such as the accumulation of rock debris from weathering or erosion and the fragmentation of rock in a contact area between two faults (see GeologyScience.com). The brecciation in Stone 23 could have been caused by pressure stresses in the rock, pushing and pulling resulting in fragmentation then the creation of a vein into which maybe quartz has filtered, cementing the fragments. Again, as is illustrated clearly on Side B, the amount of tumbling necessary to produce a smooth surface would have resulted in a very small stone. Limiting the use of coarse grit means that a small scratch remains, marring the end product, but we have a fascinating little stone to admire.

Stone 24 is a small milky quartz.

Stone 24, Side A

Stone 24, Side B

The B side shows the result of an impact on the stone. This type of line often goes deep into a stone and so cannot be removed by tumbling without destroying the stone itself. Wikipedia notes that milky quartz is a very common variety of crystalline quartz. “The white color is caused by minute fluid inclusions of gas, liquid, or both, trapped during crystal formation.” Stones W1 to W3 in this Post are other specimens of milky quartz from Gemstone Beach, in the rough unpolished state (but still very smooth). This type of quartz stone tumble polishes very well.

Stone 25 has distinct ribbons of green that caught my eye on the beach (apologies that the photos are not sharper).

Stone 25, Side A

Stone 25, Side B

The banding in this stone is a mix of mudstone (argillite) and sandstone (including some tiny quartz grains), very similar to Stone Gn14 in this Post. In such cases, I usually make sure that I do a 600 grit tumble before putting the stone to polish, to help the coarser material to polish better.

The final Post in this Series (not yet published) deals with Stones 26 to 30.

Scratches and Rough Patches, Beauty and Wonder – Thirty Small Polished Stones from Gemstone Beach/Te Waewae Bay: Part 4, Stones 16 to 20

Fossickers on Gemstone Beach.

Looking west from Gemstone Beach towards the mountains of southern Fiordland.

Te Waewae Bay waves.

Te Waewae Bay stones, just northwest of Gemstone Beach.

Stones 1 to 10, the larger ones.

Stones 11 to 20.

Stones 21 to 30, the smaller ones.

Relative size of Stones 1 and 30. $2 coin is 2.8cm across.

A great diversity of interesting and beautiful stones can be found on the coastline that runs north from Gemstone Beach near Orepuki in Southland, New Zealand. In this Series, 30 recently polished stones from that beach are described. They also illustrate some of the challenges a tumble polisher faces to obtain a completely smooth and well-polished stone. These 30 stones were selected from the smaller stones in batches tumbled in two 3lb barrels. As a result of looking closely at these stones, I realise the need to pay more attention to my inspection of stones before they pass onto the next stage of tumbling. And I need to re-examine my use of cushioning filler in the latter stages of the tumbling process. Part 1 in this Series of Posts described Stones 1 to 5, Part 2 dealt with Stones 6 to 10, and Part 3 examined Stones 11 to 15. The five stones featured here are slightly smaller than the first 15.

Stone 16 is perhaps one of the most beautiful four stones of the 30, and in addition it is among the best polished. It is a hematite jasper with some white quartz in it.

Stone 16, Side A

Stone 16, Side B

I have noticed that the brightest of the red jaspers on Gemstone Beach tend to have hematite in them. The following is taken from a November 2023 TumbleStone Blog Post on a Gemstone Beach hematite jasper: As Britannica notes, hematite is a heavy and relatively hard oxide mineral, ferric oxide (Fe₂O₃). It makes up the most important iron ore because of its high iron content (70%) and its abundance. Its name is derived from the Greek word for “blood,” alluding to its red colour. I recently read the following comment made by Tim Weglarz on the “Great Lakes Rocks & Minerals” Facebook Group: “The grey metallic bands and red coloration… of jasper is from hematite. When hematite occurs as megascopic flakes, it is opaque and metallic. When it occurs as microscopic flakes dispersed in silica, it is translucent and blood red… The red jasper… has much smaller amounts of much finer grained hematite than the opaque metallic bands.” See “H is for Hematite Jasper” in this Post for a brief description of hematite jasper generally.

Stone 17 has some fascinating veins, white and green, which caught my eye on the beach. It is tempting to think it is jasper but not all dark red rock is. The dark red is due to the presence of iron oxide, and this can occur in a number of rock types. Stone 17 has lots of tiny quartz crystals in it, so it may be a form of quartzite.

Stone 17, Side A

Stone 17, Side B

Much of Stone 17 has not taken a good polish and it lacks shine but the veins are clear and detailed.

Stones 18 and 19 also did not tumble polish well. Stone 18 is very likely to be a jasper, and sometimes jaspers like this, with lighter coloured material, do not polish well.

Stone 18, Side A

Stone 18, Side B

An idea of varieties of jasper and difficulties in tumble polishing them can be found in “Diane’s Stone, and an Introduction to Jasper”.

Stone 19 has a variety of material in it, some of which appears crumbly and did not not take a shine.

Stone 19, Side A

Stone 19, Side B

It was the pink in the stone that caught my eye on the beach, but I have mixed success in polishing such stones. Usually I am able to cull crumbly stones at an early stage in the tumbling process through the inspection I undertake between stages. However, sometimes my optimism that a stone will turn out to be ok overrides my critical judgement.

Stone 20 is a gorgeous little jasper that I struggled to get good images of. Perhaps the sunlight was not bright enough, or maybe the slight roundness of the surfaces introduced subtle reflections. Unlike most of the other stones, which had two main faces, Stone 20 has three main faces.

Stone 20, Side A

Stone 20, Side B

Stone 20, Side C

Hematite is again present in the stone, and I suspect it contributes to the bright yellows, oranges and reds.

Part 5 in this Series examines Stones 21 to 25.

Scratches and Rough Patches, Beauty and Wonder – Thirty Small Polished Stones from Gemstone Beach/Te Waewae Bay: Part 3, Stones 11 to 15

Stone fossickers on Gemstone Beach.

Gemstone Beach, looking northwest.

Te Waewae Bay beach, near Waimeamea River mouth.

Waves sweeping up Gemstone Beach, tumbling stones.

Stones 1 to 10, the larger ones.

Stones 11 to 20.

Stones 21 to 30, the smaller ones.

Relative size of Stones 1 and 30. $2 coin is 2.8cm across.

In this Series, 30 recently polished stones from Gemstone Beach/Te Waewae Bay are described. They illustrate the great diversity and beauty of stones that can be found on this beach, as well as some of the challenges a tumble polisher faces to obtain a completely smooth and well-polished stone (if that’s their aim). These 30 stones were selected from the smaller stones from batches tumbled in two 3lb barrels. Initially I thought all the stones in these two batches ended up nice and smooth. However, looking at their photos, I noticed tiny holes, bruises, scratches and rough patches on many of them. I need to pay more attention to my use of cushioning filler in the latter stages of the tumbling process. Part 1 in this Series of Posts described Stones 1 to 5 and Part 2 dealt with Stones 6 to 10. The five stones featured here are slightly smaller than the first ten.

Stone 11 is a small grey stone with a faint hint of blue.

Stone 11, Side A

Stone 11, Side B

When I saw it on the beach, the thin dark veins stood out. Later, while turning the stone for photographs, sunlight glinted off a couple of small areas, probably mica crystals. Some can be seen at the bottom right in the close-up of Side A above.

Stone 12 is a variation of spotted argillite, as is Stone 3 (see Part 1) and Stone 14 (below).

Stone 12, Side A

Stone 12, Side B

Stone 12 is darker in colour than Stone 3, and its “spots” are slightly more clearly defined. There is quite a range of spotted argillites on Gemstone Beach.

Stone 13 is an astonishing cluster of small white spots. They are packed tightly together.

Stone 13, Side A

Stone 13, Side B

This is likely to be a volcanic stone, originally full of tiny gas bubbles. Those bubble holes (“vesicles”) were infilled slowly by a white mineral as hot water flowed into them. These white “spots” are called “amygdales” (or “amygdules”), from the Latin and Greek words for almond, reflecting the almond-shape of many such spots. Stones W30 to W33 in this Post are other examples of amygdaloidal stones from Gemstone Beach, and a more detailed explanation of their formation follows them.

Stone 14 has some similarities to Stone 3 – a dark green fine-grained sedimentary stone with seemingly out-of-focus light-coloured spot-like patches.

Stone 14, Side A

Stone 14, Side B

They are both most likely to be types of spotted argillite (along with Stone 12). Stone 14 also has some very fine veins in it, some dark and some light. At first sight, it is tempting to think Stone 14 could be a “variolite”, because of its appearance. Variolites contain small spherical or globular structures, called varioles, in a fine-grained matrix. Varioles are lighter coloured than the host rock and the photo of a specimen on Wikipedia looks very similar to Stone 14. However, variolites are volcanic in origin, usually basaltic. Mindat notes that varioles have quite a different origin than spherulites, which are also small rounded bodies that commonly occur in igneous rocks (such as spherulitic rhyolite, as can be found at Slope Point – see, for example, the second stone in this Post).

Stone 15, like Stone 4 and Stone 9, is volcanic in origin with light-coloured crystals in it. Unlike Stone 4, the crystals are densely packed and in contrast to Stone 9, the surrounding rock material is not as dark.

Stone 15, Side A

Stone 15, Side B

The tiny often oblong crystals in the stone are fascinating, and scattered amongst them are some black and some silver (mica?) crystals:

Greater close-up of Side A

Greater close-up of Side B

The next Post in this Series examines Stones 16 to 20.

Scratches and Rough Patches, Beauty and Wonder – Thirty Small Polished Stones from Gemstone Beach/Te Waewae Bay: Part 2, Stones 6 to 10

Part of Te Waewae Bay coast, from Gemstone Beach in south to Waimeamea River mouth and lagoon, my fossicking area. Source: Google Maps.

Mouth of Taunoa Stream, not far from carpark.

Hidden house, Gemstone Beach.

Gemstone Beach stones.

Stones 1 to 10, the larger ones.

Stones 11 to 20.

Stones 21 to 30, the smaller ones.

Relative size of Stones 1 and 30. $2 coin is 2.8cm across.

In this Series, I present 30 recently polished stones from Gemstone Beach/Te Waewae Bay. They illustrate the great diversity and beauty of the pretty stones of this beach, as well as some of the challenges a tumble polisher faces to obtain a completely smooth and well-polished stone (if that’s their aim). These 30 stones were selected from the smaller stones from batches tumbled in two 3lb barrels. Part 1 described Stones 1 to 5. The next five stones, featured here, are slightly smaller than the first five.

Stone 6 is a mix of colours and shapes. On the beach, the bright sweep of opaque white on Side A caught my eye, then the green (most likely epidote), then, upon closer inspection, the intriguing veins.

Stone 6, Side A

Stone 6, Side B

This is a good example of a small stone that reveals more and more as you look closer at it. Though tiny holes are also among the things revealed.

Stone 7 is an example of a stone that from a distance appears to have a simple makeup – some light-coloured patches and some slightly darker patches.

Stone 7, Side A

Stone 7, Side B

But closer inspection reveals an intricate mosaic of what could be tiny crystals in an irregular latticework pattern. It’s an amazing and beautiful stone, but I don’t know what kind it is. A few tiny scratches can also be seen.

Stone 8 has contrasting sides. It’s a type of quartz, I call it a sugary quartz because of the small granular-like crystals that make it up. Side A has a brown hue, Side B has a whiter hue.

Stone 8, Side A

Stone 8, Side B

The difference in colour will be due to variation in the presence of a brown mineral, most likely iron oxide. Stones of this “sugary” composition can be hard to get completely smooth through the tumbling process, with tiny grains coming loose from the surface. However, I like how they look and have had success with a number of them.

A small black and white volcanic stone, Stone 9 is full of amazing tiny white crystals.

Stone 9, Side A

Stone 9, Side B

The crystals are elongated and appear to float throughout the black material. Generally speaking, the longer it takes for volcanic rock to cool, the larger the crystals in it will grow, having longer time to form. In this Post on igneous stones from Gemstone Beach, Stones W43 to W56 illustrate the diversity of white crystal shapes and sizes that can be found.

Stone 10 looks like a pale-coloured mudstone, but it has some interesting dark veins or lines in it. These are likely to be dendrites, thin branching lines of crystals, often of some variety of manganese oxide (or iron), that grow over the surface of a stone. They are found in cracks or along bedding planes. The word “dendrite” is from the Greek word for “tree”, referring to its branching appearance.

Stone 10, Side A

Stone 10, Side B

Mindat has some good photos of dendrites and Sandatlas has a technical explanation of their growth. Thornton provides some NZ examples of dendrites in agates in her book “Gemstones” (page 15 here). Dendrites are often given as examples of “pseudofossils”, natural objects that may be mistaken for fossils of, for example, a plant leaf.

Part 3 in this Series examines Stones 11 to 15.

Scratches and Rough Patches, Beauty and Wonder – Thirty Small Polished Stones from Gemstone Beach/Te Waewae Bay: Part 1, Stones 1 to 5

Orepuki, Southland.

Gemstone Beach, in front of the carpark.

Looking northwest from in front of the carpark.

Gemstone Beach stones.

Stones 1 to 10, the larger ones.

Stones 11 to 20.

Stones 21 to 30, the smaller ones.

Relative size of Stones 1 and 30. $2 coin is 2.8cm across.

Just before Christmas, I finished polishing some of the stones I had collected from Gemstone Beach and nearby in early 2023. They were tumbled in two 3lb barrels, the final stage for each batch being a tumble in tin oxide polish for just over two weeks, followed by burnishing in borax (for three days for one barrel, for five days for the other). Most of the stones would have been tumbled prior to this in 600 grade silicon carbide grit; all of them were tumbled in 400 grit before that; and some of them, those needing the most smoothing, would have been first tumbled in 220 grit.

In this Series of Posts, I present 30 of the smaller stones, to show their character as well as the difficulty of tumble-polishing. Throughout the stages of tumbling, I carefully sort through stones to try to make sure that they are as smooth as possible before they go on to the polish tumble. At first glance, I thought all the stones in these two batches were nice and smooth, and that they ended up well polished. However, looking at these photos, I can see the need for me to be even stricter before the final stage, as tiny holes, bruises, scratches and rough patches are apparent on many of the stones. I need to pay more attention to cushioning filler – I am currently reducing my use of plastic beads and using very small stones instead. I didn’t seem to get the balance of filler to stones quite right with these batches. Nevertheless, what is also apparent is the often complex and beautiful character of these stones, truly natural wonders from a Southland beach.

The first five stones are the larger of the 30, though the largest, Stone 1, is only about 5 cms wide. It is an example of a stone made up of lots of different little bits. In terms of appearance, it has many shades of grey. In constitution, it is a breccia, meaning that it consists of angular fragments of stone that have been compressed together in a matrix – see University of Auckland Geology. [If the fragments, known as clasts, were rounded, it would be a conglomerate, the fragments having been eroded by travel from their source before being compressed.]

Stone 1, Side A.

Stone 1, Side B.

Some of the fragments are likely to be argillite, a mudstone, but there are a lot of other little things in there too, various grains and crystals. Some of the crystals reflect the light when held at an angle. This diversity of material in the stone also explains why it did not take a uniform polish – for example, some of the fragments, grains or crystals will be softer.

Stone 1 is a dark stone, but Stone 2 is much lighter in appearance (though with a few dark patches).

Stone 2, Side A.

Stone 2, Side B.

One of the black patches on Side B is particularly striking. Again, this stone is a breccia, with the dark patches being angular clasts. Much of the light-coloured material could be quartz of some form. Quartz is a form of silica and is among the most common of all rock forming minerals. It is found in a wide variety of types in different kinds of rocks. It tends to tumble polish well.

Stone 3 is spotted argillite, a fine-grained mudstone. The “spots” are not perfect, many are not well-formed, but the colour variation they introduce leads to an interesting visual pattern. On Gemstone Beach, argillite is often a solid green colour, but this is an example of one of the variations that occurs. The green of Stone 3 is highly likely to be caused by the mineral epidote which in New Zealand is widespread in veins in greywacke, schist and granite. Epidote is in fact the main mineral in the iron-rich mudstones of Otago and Southland, including argillite.

Stone 3, Side A.

Stone 3, Side B.

Stone 3 has come through the tumbling process reasonably well, though there is a slight scratch on Side B. In this Post on green stones on Gemstone Beach, 12 other specimens of spotted argillite are presented (Stones Gn20 to Gn31). I suggest there that “spots” occur when argillite comes under increased pressure and heat, more than is usual for a sedimentary rock. During this process, certain minerals become concentrated in specific areas.

Stone 4 is probably of igneous origin, most likely volcanic. It is quite different from the previous three.

Stone 4, Side A.

Stone 4, Side B.

It is mainly dark, yes, and has a mixture of material in it, including white crystals (or are they clasts?), but it also has some intriguing subtle linear shapes. It was those shapes that caught my eye on the beach, and it is their existence that defines the individuality of the stone.

Stone 5 appears to be made up primarily of black and white crystals, with minerals providing pastel colour patches of orange/pink and light green.

Stone 5, Side A.

Stone 5, Side B.

The black crystals help create contrasting halves in the stone, with the pastel colours providing a subtle delicacy. The orange/pink is likely to be due to the presence of orthoclase feldspar, a potassium-bearing member of the alkali feldspar family – it is orthoclase feldspar that gives granite its pink component. The green patches are likely to be caused by the mineral epidote (mentioned in relation to Stone 3 above). Stone 5 has tumbled well, though Side A has some tiny rough areas.

The next Post in this Series examines Stones 6 to 10.

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: 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: