A Blog About Stone Gathering, Tumbling and Polishing, and Rocks and Landscapes, from New Zealand – With Musical Interludes (john.tumblestone@gmail.com)
Chromium-bearing Diopside, also known as Chrome-Diopside, is a rich intense green. I found this small stone with a dark green mineral in it on Gemstone Beach on a warm Sunday afternoon in March 2024. There are some interesting white “swirls” in the stone as well. I am very grateful that, when I posted it in this Group, a Nelson member commented that it looked a lot like the Chromium in Diopside in Semi-nephrite he knew from his local region. While Semi-nephrite is said to be present on Gemstone Beach, I suspect this stone is Hydrogrossular Garnet. I featured it in my 2025 Calendar in the month of January. Diopside is a mineral which includes both silica and magnesium as key components, usually with the presence of iron providing a light green hue. If chromium is present, this intense green occurs. One interesting source on Chrome-Diopside is “Exploring Chromium Diopside: Properties and Applications”.
Wave moving up the Taunoa Stream, Gemstone Beach this morning.
I stayed away from the beach for a few days – it was cold and windy and often wet. So I caught up on Blog Posts and leisure reading instead. This morning saw no wind or rain though it was cloudy. So I ventured out again. It was only seven degrees when I arrived at Gemstone Beach at 9.50am, and nine degrees when I left two hours later. But it was comfortable on the beach, wearing my hat and scarf and puffer jacket. Throughout this time, there seemed to always be two or three cars in the carpark and/or six to eight people on the beach. The tide was coming in, high tide being scheduled for 1.46pm, so I didn’t wander too far past the Taunoa Stream, turning back after 45 minutes. I found a number of interesting stones this morning, a handful of trace fossils, and one decent sized hydrogrossular garnet. But the main prizes today were five small poppy jaspers and a stuning breccia.
Wave moving up the Taunoa Stream, Gemstone Beach this morning.
This part of the cliff is usually buried in sand.
Gemstone Beach stones.
Gemstone Beach stones.
My finds today.
The 5 poppy jaspers I found.
I picked up the first poppy jasper just ten metres after crossing the Taunoa Stream, thinking then that this was going to be the highlight of the fossick. Then another two appeared west of there. On my way back to the carpark, I spent some time looking in the Taunoa Stream itself and found another. The final one was on the beach halfway between the stream and the carpark.
Poppy jasper #1.
Poppy jasper #2.
Poppy jasper #3.
Poppy jasper #4.
Poppy jasper #5.
Another stunning find was this pale brecciated stone – I don’t think I’ve seen anything to rival it:
Exquisite brecciation.
Other side of stone.
Another really interesting breccia:
I find the pattern of white patches in this quartzite(?) to be very attractive:
Every now and again I spot a stone like this, with pale blue through it – it is hard not to add it to my bag of finds:
On the beach, I could see something was going on in the central vein of this next stone – it took the close-up image to revel the complexity of it:
Another veined stone that caught my eye, probably rhyolite:
A multi-veined stone that’s been pushed around a bit:
I didn’t spot many trace fossil stones, but here are two of the five I picked up:
One side of the first trace fossil stone.
The other side of the first trace fossil stone.
Along the edge of the first trace fossil stone.
The second trace fossil stone.
I am constantly amazed at the beauty and diversity that can be found on Gemstone Beach as shown in these stones. Yes, it can take time to hunt out the really stunning ones. And some fossicks are better than others. But as revealed in the photos, geological processes, with pressure and heat and the creative forces of deep water and fiery volcanoes, produce wonderous bright colours and patterns. I’m always left with a sense of wonder.
“A Sense of Wonder” is a song by Van Morrison (YouTube video below). Note that it includes references to his youth in Belfast, Ireland. Newtonards, Comber, Gransha, and Bollystockart are all roads in that city. “Spike and Boffyflow” are two people that Morrison refers to in the liner notes for the album – they are also partly a reference to an instrumental of the Chieftains, written by Morrison, which was entitled “Boffyflow and Spike”.
“A Sense of Wonder” by Van Morrison (1984)
I walked in my greatcoat Down through the days of the leaves. No before after, yes after before We were shining our light into the days of blooming wonder In the eternal presence, in the presence of the flame.
Didn’t I come to bring you a sense of wonder Didn’t I come to lift your fiery vision bright Didn’t I come to bring you a sense of wonder in the flame.
On and on and on and on we kept on singing our song Over Newtonards and Comber, Gransha and the Ballystockart Road. With Spike and Boffyflow, I said I would describe the leaves for Samuel and Felicity Rich red browney, half-burnt orange and green.
Didn’t I come to bring you a sense of wonder Didn’t I come to lift your fiery vision bright Didn’t I come to bring you a sense of wonder in the flame.
It’s easy to describe the leaves in the autumn And it’s oh so easy in the spring But down through January and February it’s a very different thing.
On and on and on, through the winter of our discontent When the wind blows up the collar and the ears are frostbitten too I said I could describe the leaves for Samuel and what it means to you and me You may call my love Sophia, but I call my love Philosophy.
Didn’t I come to bring you a sense of wonder Didn’t I come to lift your fiery vision bright Didn’t I come to bring you a sense of wonder in the flame...
Wee Alfie at the Castle Picture House on the Castlereagh Road Whistling on the corner next door where he kept Johnny Mack Brown’s horse “O Solo Mio” by McGimsey And the man who played the saw outside the city hall Pastie suppers down at Davey’s Chipper Gravy rings, wagon wheels, barmbracks, snowballs.
A sense of wonder…
The next Post in this Series highlights five green-hued stones found on Gemstone Beach. An Index to this Series is here.
This afternoon I spent just over two hours on Gemstone Beach. I arrived at 2.20pm, two hours before low tide. It was 13 degrees throughout the fossick, with a strong breeze. I chatted to a couple from Arrowtown as I left, identifying three or four of the handful of stones they had found.
Gemstone Beach this afternoon. Looking west. A small group near the mouth of the Taunoa Stream.
Looking east from 100 metres east of the Taunoa Stream.
Gemstone Beach stones.
On the way back, the beach in front of the carpark, viewed from just west of the Taunoa Stream.
Seagulls over the breakers on Gemstone Beach.
Gemstone Beach seagulls.
The hydrogrossular garnets I found today were mainly small and, as with the previous fossick, I spotted very few trace fossil stones. I did find one small poppy jasper and the occasional interesting other kind of stone. Twelve of this afternoon’s finds are featured below.
Gemstone Beach stones.
More Gemstone Beach stones.
Today’s finds.
The largest stone I collected today is this rhodonite. Rhodonite is primarily composed of manganese silicate, its colour varying from light pink to deep red. It is similar in colour to thulite but often features black markings caused by manganese oxides:
Large rhodonite stone.
Other side of rhodonite stone.
Another glassy stone that has been suggested to me is chromite in quartz, two also having been found yesterday:
Chromium in quartz?
Holding the stone up to light.
A black and white stone where I suspect the white material could be hydrogrossular garnet, kind of similar to one I found on Sunday:
I found two small poppy jaspers, the first having a little green epidote in it:
Small poppy jasper with epidote.
Other side of stone.
Two finds with different types of brecciation (re-cemented fragmentation), the first the result of tectonic pressures on the whole stone, the second being limited to a vein:
Brecciated argillite.
Brecciated vein.
Next are the two largest of my hydrogrossular garnet finds – the first is partly transparent, the second is opaque and very waxy (so that water beads off it quickly):
Partly transparent ydrogrossular garnet.
Held up to the light.
Opaque hydrogrossular garnet.
Water moves off the waxy surface.
And now a couple of green-hued stones. The first is what is said to be the typical pistachio-green hue of epidote (though epidote causes a range of greens):
Probably green epidote.
The second is perhaps a form of spotted argillite (Stones Gn2 to Gn31 in this Post are examples of spotted argillite):
A type of spotted argillite?
A small banded argillite, a good example of an indurated banded mudstone:
Down near the Waimeamea River Lagoon, lots of stones.
On the beach, many stones simply look plain and uninteresting, especially when they are dry. Seeing them when they are wet is a different experience – their colours come alive. Picking one up and viewing it at close quarters reveals even more. Veins appear, patches emerge, patterns become clearer. And when I see a close-up photo of a stone, its history and complexity and beauty are all revealed, and I can but marvel. A simple stone, that turns out to be not so simple.
Dry stones, Gemstone Beach.
A potentially interesting stone.
The stone wet. What at first sight appeared to be a simple green-hued stone.
Other side of stone.
I always feel privileged to be on the beach looking for such “simple stones”. There’s no better way to spend an hour or three. T0 quote, and slightly change, some lyrics from a “Simple Song”: “Here’s a simple stone, won’t stop the rain from coming down or your heart from breaking. Just a simple stone, it’s never gonna turn this day around, stop the earth from shaking. It’s just a simple stone…” And sometimes finding such a stone CAN turn your day around.
Passenger’s “Simple Song” (lyrics at end of Post):
Today I fossicked on Gemstone Beach again. I arrived after lunch, a couple of hours before low tide. The weather was sunny with only a light breeze, the temperature being around nine degrees. A handful of others were there, mainly in front of the carpark.After crossing the Taunoa Stream, I came upon the local gold miner and Tig, his small fox terrier. We had a chat, I patted the dog, then I continued along to the Waimeamea River Lagoon. I passed another bearded fossicker on his way back but otherwise no-one else was that far down the beach. I got back to the carpark two and a half hours after I arrived, the temperature at that stage being ten degrees.
Gemstone Beach today.
A few more stones on the beach today.
Still some patches of sand.
Down near the Waimeamea River Lagoon, lots of stones.
My finds today.
Another 18 of my finds today are featured below. This one is a great example of how close-up photos reveal what the naked eye can’t easily see. In this case, tiny white spots appear, along with details of the differently-coloured patches in the small stone:
Some stones are transparent and holding them up to the light can tell you more about what is in them or confirm your suspicions from what you initially see:
Small transparent hydrogrossular garnet.
Most stones look very similar no matter which side you view. The occasional one surprises you when you turn it over. This is an example of a stone that incorporates material from both sides of a contact boundary:
One side of stone.
Other side of stone.
I have come to recognise a few different types of stones on Gemstone Beach. One is thulite – this find is a good example, with its distinctive clouds of pink and i small fragments of white quartz:
Thulite.
However, are all pink stones thulite? No. Sometimes I have found pink rhodonite here. This next stone is not easy to identify with any certainty – thulite or rhodonite or something else? Its pink is less intense, there are no quartz fragments, and do the darker patches hint at the maganese oxide to be found in rhodonite?
Thulite or rhodonite or ?
Other side of stone.
My next two finds are quite different from each other but I wonder whether both have significant amounts of hydrogrossular garnet in them. They are not obvious specimens of garnet but both have elements suggestive of it. I found the first in a flow of water seeping through the bank of stones holding back the Waimeamea River Lagoon. It is the largest stone I have collected for some time. I thought it might be quartz, but the pattern of its colours can be found in hydrogrossular garnet. It has a very smooth surface that has maybe a hint of waxiness:
Quartz or hydrogrossular garnet?
Other side of stone.
The second candidate for hydrogrossular garnet looks like it could be a mudstone, and it is also quite large. At times I think I spot a garnet on the beach but it turns out to be a mudstone angled in such a way that the sun glints off it. Again, it doesn’t really feel waxy but it lcks the opaqueness I associate with mudstone and the vein material is very suggestive of hydrorossular garnet:
Mudstone or hydrogrossular garnet?
Other side of stone.
Unlike the previous three fossicks here, I found very few trace fossil stones today but quite a few hydrogrossular garnets. There was no doubt about them. Here are four, of various colours and textures:
Hydrogrossular garnet.
Hydrogrossular garnet.
Hydrogrossular garnet.
Hydrogrossular garnet.
And a hydrogrossular garnet with a lot of dark diopside in it:
Hydrogrossular garnet with diopside.
The next two finds are very glassy. When I first came across this type of stone, I was told it was likely a form of hydrogrossular garnet. More recently, I have been told it could be chromite in quartz. I’m not sure how to confirm one way or the other. The first find below is a typical green for this kind of stone (I found it about 10 metres past the gold man), the second is unusually white:
Chromite in quartz?
Chromite in quartz?
Two jasper stones I found today, the first an intense red almost mossy in character, the second a brecciated (fragmented) duller opaque variety but with a touch of green epidote:
Jasper.
Brecciated jasper.
Some stones have clealy defined bands or lines, like this banded argillite:
Banded argillite.
Other stones have less defined edges to the different colours in them, like this one (which could in fact be a hydrogrossular garnet):
Other side of stone.
Simple stones, but endlessly fascinating.
Lyrics for “Simple Song” by Passenger (Michael Rosenberg), released 2017
Here’s a simple song Won’t stop the rain from coming down Or your heart from breaking Here’s a simple song It’s never gonna turn this day around Stop the earth from shaking It’s just a simple song Nothing right or wrong You can sing along if you want to
Well, I know it’s not been easy But easy ain’t worth singing about Yeah, I know, I know The time goes slow But it’s always running out
Here’s a simple song Won’t stop the rain from coming down Or your heart from breaking Here’s a simple song It’s never gonna turn this day around Or stop the earth from shaking Yeah, it’s just a simple song Nothing right or wrong You can sing along if you want to
Well, I know it’s far from simple But simple ain’t worth worrying about Yeah, I know, I know It’s time to go I think I keep on finding Everything seems to be about timing
Here’s a simple song Won’t stop the rain from coming down Or your heart from breaking Just a simple song Never gonna turn this day around Stop the earth from shaking It’s just a simple song Nothing right or wrong You can sing along if you want to
Whoah, it’s just a simple song Nothing right or wrong You can sing along if you want to
The next Post in this Series covers another Gemstone Beach fossick conducted the next day. An Index to the Series is here.
Chrissy and I arrived at Gemstone Beach at 12.15 pm, 90 minutes before low tide. That gave us enough time to walk down the beach a fair distance and get back well before the tide came in. At high tide, the waves come right up to the foot of the cliffs which back the beach. Fossickers must make sure they avoid this danger. The temperature upon our arrival was only nine degrees but it was sunny and there was no wind, leading to a comfortable afternoon. We reached the Waimeamea River Lagoon just as the tide turned.
Chrissy just after crossing the Taunoa Stream, looking back at a passing horse and rider.
Chrissy on the stones closer to the Waimeamea Lagoon.
The area of wet stones along the edge of the waves is the best place to fossick. Wet stones show their colours and patterns.
Lots of sand on stretches of the beach where there has usually been stones in the past. Looking back towards the Taunoa Stream and carpark.
The bank of stones in front of the Waimeamea Lagoon.
Driftwood in the dry part of the Waimeamea Lagoon.
Looking west along the beach, the figure of fellow fossicker Jason looming up.
Near the Lagoon, as we were walking westwards, we met Jason, a fellow member of the Southland Geological and Lapidary Club, who was walking eastwards. We enjoyed a good chat and sharing of finds before parting.
Chrissy and I left the beach at 3.40 pm after a productive three and a half hours fossick. Just after arriving, we had spotted a horse and rider emerging from the slightly misty distance (see photos below). Horses appear sometimes on the beach- see for instance “Fossicking with Oliver, Te Waewae Bay, Sunday 26 March 2023” and “Forty-Three Finds and Four Horses on Gemstone Beach, Wednesday 5 March 2025”. Then, as we were getting close to the carpark at the end, an aircraft flew overhead, landing on the beach halfway between us and Monkey Island – the first time I had seen this happen!
The horse coming….
…and the horse going.
The aircraft overhead.
I collected around 90 stones this afternoon, 16 of which are featured below. The first is one of my most intriguing finds, a melange of elements with a bright red mineral cloud on one side, probably iron oxide:
Bright dark red mineral cloud.
Other side of stone.
Next, a thulite stone with some bright pink patches:
Thulite stone.
Other side of thulite stone.
A variety of types of stones with thulite in them can be found on Gemstone Beach. The pink can be bright and intense or it can be quite pale. Thulite is the national gemstone of Norway where it was first discovered in 1820. It is the pink to reddish variety of the mineral zoisite. As Minerals.net reports, “The color of thulite is caused by the element manganese in its composition. Thulite often occurs associated with quartz, and is sometimes mottled with streaks or spots of white quartz.”
I found a small poppy hematite jasper, a red type of orbicular jasper. It has a thin white vein and there’s also some tiny patches of a white mineral on one side:
Poppy (orbicular) hematite jasper.
Other side of poppy jasper.
Orbicular jaspers form due to the presence of minerals which crystallise in concentric layers around a central point, giving rise to orb-like structures. The orbs can be tiny or a bit larger. I found a very rare white orbed jasper during the final fossick of my March trip this year which has much smaller orbs than this find.
The following small stone caught my attention because of the dark blue areas on it. It has some great intense green epidote in it, and some white quartz, but the blue is more unusual:
Quartz, epidote and a blue m
Other side of stone.
I started spotting some hydrogrossular garnets today after not seeing them during the first two fossicks on Gemstone Beach this month. Of the two largest, one was a smoky brown colour, the other having a bright orange/yellow mineral in it:
Smoky brown hydrogrossular garnet.
Hydrogrossular garnet with bright orange/yellow.
Hydrogrossular is a massive form of garnet rather than a crystal form. It was first identified by a New Zealander, Colin Hutton, in the 1940s. He analysed some stones from Nelson, the other main area than Gemstone Beach that hydrogrossular can be found in this country. Hydrogrossular garnet is one of 13 minerals first described from New Zealand and accepted as valid by the International Mineralogical Association. For further information, see my 2023 Post “First Identified in New Zealand in 1943 – Revisiting the Hydrogrossular Garnets of Gemstone Beach”.
The next find is a grey mudstone, probably argillite, with very interesting nodules and swirls:
Grey mudstone.
Other side of grey mudstone.
I also found a very small light grey banded argillite with find bands – it has a slightly glazed appearance, probably from being subject to a bit more pressure and heat during formation:
Small banded argillite.
The next find is a darker grey in areas, and the swirls at the top caught my eye on the beach. However, looking at the photographs of it, my attention moved to the textured area of crystals at the bottom:
Another textured find, a stone packed with tiny features, many of them crystals, I think:
In my as-yet-unfinished Series “Gemstone Beach And Its Stones: An Introduction For The Passing Motorist”, I have a section on stones with opaque white crystals – see Stones W43 to W63 in this Post. Since then, I’m always on the look-out for good specimens reflecting the range of types. I found these two today:
The second of these two in particular interests me – the white in it is quite intense, and the close-up photos show that the crystals, if that is what they are, have tiny grey veins in them, maybe the result of brecciation. I have a suspicion the white material is hydrogrossular garnet.
Finally, I continue to find great specimens of trace fossils in argillite. Here are four. The first is very rare, the clearly-defined traces being an interesting mix of dark and light hues in a black stone. The second has a much more subtle and faint trace. The third and fourth are good examples of types often present on Gemstone Beach.
Chrissy, far left, and some of the other people on Gemstone Beach today.
Hunting for stones is often an activity located somewhere between the beauty and the pain. A fossick can be a painful search for beautiful stones, depending on the weather or other circumstances. I arrived at Gemstone Beach at 10 am this morning with Chrissy.It felt very cold, and I didn’t really warm up completely on the beach despite my hat and scarf and heavy coat. Given the cold temperatures (about nine degrees) and especially the bitter wind, we decided not to stray too far from the carpark. Luckily the rain stayed away, moving across to the west of us.
A cold bleak Gemstone Beach today.
Chrissy at the edge of the Taunoa Stream, as far as we went today.
Chrissy, far left, and some of the other people on Gemstone Beach today.
We fossicked only as far as the Taunoa Stream, along maybe 250 metres of the beach – there were good patches of stones on about one-third of this area. There were maybe eight to ten other people there at various times. We left after one and a quarter hours. I took 37 stones away with me. Ten of them are featured below.
This find was the most interesting to me due to the tiny shapes (probably crystals) in it:
A stone with some intense green in it, though its two sides are quite different:
Other side of stone.
Another two stones with significant green in them:
A mudstone that has come under tectonic pressures which have partially fragmented it:
Mudstone with brecciation.
The red streaks in the next stone caught my eye but there’s other stuff going on in there too:
And I keep finding good quality trace fossil argillite stones – here are four, with the last two having much fainter traces than the first two:
The phrase “Between the beauty and the pain” comes from the lyrics for “Strangest Thing” by The War on Drugs:
Summer ride on a beach And howl at the day I’ve been hiding out so long I gotta find another way
Late at night I wanna see you Well, my eyes, they begin to fade Am I just living in the space between The beauty and the pain And the real thing
Now the sky is painted In a wash of indigo I’ve been holding on too long In the howling of this cold
Recognise every face But I ain’t got everything I need If I’m just living in the space between The beauty and the pain It’s the strangest thing
Yeah, should-haves surrounding me Surrounded by the whole Surrounded by no other I wanna ride home
Yeah, I can run slowly Don’t run away again Yeah, I can run the stones Don’t run away again I wanna run, I wanna run
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 Gn62therecontaintrace 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.
I found this stone on Gemstone Beach, Southland, in September 2024 – see the end of the Post “Sunday 8 September 2024: Fifteen Finds from a First Gemstone Beach Fossick”. It is a handful, nine centimetres wide. Argillite is a sedimentary rock that sometimes shows a banding, reflecting layers of different coloured sediments. On Gemstone Beach, banded argillites can be found in hues of green, grey, black and brown. Sometimes I think that this particular stone is brown, sometimes I wonder if it is grey – colour perception is subjective. Many of Gemstone Beach’s banded argillites appear to have been subject to more heat during formation than other argillites, their bands looking as if they melt into each other, like pottery glaze. They tumble polish well. This one is too big for me to tumble polish – it sits outside in the garden at my home in Whanganui and looks brilliant after rain.
A recent Series featured 30 stones that I had sold to Doug Davidson, the journalist for Whanganui’s River City Press. Here is the article that came out of his interview with me. It is also now available on the newspaper’s website.
I was recently interviewed about stone collecting by Doug, a journalist for Whanganui’s River City Press. Afterwards he asked to buy some of my polished stones so I picked out 30 Gemstone Beach stones for him.When he took my photo for the article, Doug got me to hold a printout of the 30 stones.
Southland’s Gemstone Beach, located near the small town of Orepuki, has a great diversity of colourful and interesting stones. Their value lies NOT in being precious gemstones (because they are not!). But their value lies in the fascinating features and patterns within each stone, often only fully revealed in close-up photos. Tumble polishing the stones applies a permanent clarity to their surface so that their inherent visual art is always on display. My Post “March 2019 Stone Collecting Trip to Southern New Zealand – Gemstone Beach, from the Car Park to the Waimeamea River Mouth” describes the kilometre long stretch of beach that I walk in order to find these stones. I usually spend around three hours at a time there on each visit. In March 2019, in five visits, I collected about 18 kilograms of stones to take home to Whanganui to polish. These days, I pick up less stones, being much more selective, but I always find fascinating ones and often something new and unexpected (see the end of this Post, below).
To continue with Doug’s 30 stones…
Part One in this Series, covering Stones #1 to #5, is here.Part Two describes Stones #6 to #11; Part Three is about Stones #12 to #17; and Part Four features Stones #18 to #23. The final seven stones, the smallest, are now presented.
Stone #24 is a very strange stone and a mystery to me:
Stone #24, unknown, side A.
Stone #24, side B.
It looks like there is a lot of quartz in the stone but the top part of it has a significantly different appearance to the lower part. There is an interesting boundary band between the two as well. The top part has some different-hued patches in it but what catches the eye are the thin veins of a very dark mineral running across it. When I saw this on the beach, it immediately stood out as unusual. I wondered if it was a fossil of some kind, or a shell embedded in a stone. The photos show that it is all one stone, but with intriguing markings.
Stone #25 is the same type as Stone #9 (in Part Two), probably a quartzite with a fine lace-like tracery of mineral through it:
Stone #25, side A.
Stone #25, side B.
However, whereas the tracery is yellow in Stone #9, it is green in Stone #25. Patterns like these always catch my eye on the beach. The green is caused by epidote, a mineral we have seen before in Doug’s stones.
Stone #26 consists of small rock fragments (called “clasts” by geologists) from a variety of sources, making it “polymictic” in contrast to Stone #6 (in Part Two) and Stone #19 (in Part Four)which are “monomictic” (their clasts come from only one source):
Stone #26, side A.
Stone #26, side B.
However, is Stone #26 a breccia or a conglomerate? As I have previously noted, in a “breccia” stone, the clasts have not travelled far before being cemented together so they are angular and sharp. In a “conglomerate”, the clasts have undergone some rounding from the travel they have experienced, usually from water, prior to being cemented together. There is maybe some rounding of some of the fragments in Stone #26 but most fragments are angular, so it’s probably ok to call it a breccia. However, some stones are a mix, not fitting clearly into either category. It’s not unusual to find stones like that – the neat general categories of geologists are very useful but individual stones do not always line up precisely with them.
Stone #27 is a white quartzite:
Stone #27, side A.
Stone #27, side B.
Such quartzites appear to have thick “clouds” of intense mineral within them. There are some similarities to what I called a “canyoned” green quartzite I found on Gemstone Beach in March 2023. Another similar stone is the second one in this Post, a very dark green quartzite I found in March this year. On side B of Stone #27, you can see some holes that have not been smoothed out by the tumble polishing. They can ruin the look and the feel of a polished stone. However, to get rid of the holes in such a small stone would wear it away to practically nothing, and the stone is too interesting to lose.
Stone #28 is the kind of stone as Stone #21 (Part Four), a quartzite full of the green mineral epidote:
Stone #28, side A.
Stone #28, side B.
There is a prominent vein of translucent or transparent quartz running through side A of this stone. Such a “vein” is an infilled crack. When rock comes under pressure and stress, it fractures, and cracks of different sizes open up. This allows hydrothermal fluids, carrying dissolved minerals, to enter the gaps in the rock. Over time, the dissolved minerals precipitate out of the hot water. Crystals, such as quartz, grow within the cracks and fill them. Often, as the stresses on the rock change their orientation over time, veins can crosscut and even overlie each other.
I often discover that the smallest stones I pick up on Gemstone Beach are the most fascinating ones. When wet on the beach, they can catch my eye despite their small size. But their full beauty can’t be appreciated until close-up photos are viewed. Stone #29 is such a stone – it turns out to consist of a patchwork of colours and veins:
Stone #29, side A.
Stone #29, side B.
It’s a stone that has been subject to a lot of tectonic pressures and its veins have been flooded with different minerals at different times, contributing to its delightful patchwork.
Stone #30 is the smallest of Doug’s stones but to me it is the most gorgeous:
Stone #30, side A.
Stone #30, side B.
Like a lot of the stones I find and polish, it is mainly a mystery. I don’t know exactly what type of rock it is, though it will be one of the volcanics. It is amygdaloidal, like Stone #23 (Part Four) – a stone with many tiny vesicles (gas holes) that have been infilled with minerals. But I don’t know what these minerals are. When I picked up this stone from the beach and looked at it closely, I knew it would be interesting. But the photos made me gasp as they revealed a whole ‘nother world of tiny detailed beauty.
The rest of Doug’s 30 stones feature as follows: Stone #1 to #5 = Part One; Stones #6 to #11 = Part Two; Stones #12 to #17 = Part Three; Stones #18 to #23 = Part Four.
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Gemstone Beach has provided me with many fascinating discoveries – photos of six of my most valued are below. The first is a fossil coral, the only one I know to have been found on the south coast (and it’s likely to be very rare even for New Zealand). I glimpsed it on the beach in June 2020. Such a stone is the official State stone of Michigan where it is known as a petoskey stone. See “C is for (Fossil) Coral”. The second stone below is a bright pink thulite I found in September 2024. Thulite is the national gemstone of Norway where it was first discovered in 1820. I can sometimes find one or two thulites on a visit to Gemstone Beach, but not always, and the quality of their pink varies. More information on this mineral can be found in “January 2022, Stone of the Day #5 – A Little Pinky”.
Fossil coral stone, Gemstone Beach, when found.
Polished fossil coral stone, Gemstone Beach.
Thulite, Gemstone Beach.
The third stone below is probably chromium in diopside in hydrogrossular garnet, found in March 2024 (“chromium in diopside” is the intense green colour) – I used it for the month of January in the 2025 TumbleStone Calendar. I found the fourth stone, a poppy (orbicular) jasper, in September 2024. GeologyScience states: “The distinctive orbicular patterns form due to the presence of various mineral impurities or inclusions within the silica solution. These impurities can include minerals such as hematite, goethite, chlorite, or other oxides and hydroxides, which crystallize in concentric layers around a nucleus or central point, giving rise to the orb-like structures.”For a similar poppy jasper plus more information on orbicular jasper, see “O is for Opaque Orepuki Orbicular Jasper”.
Chromium in diopside in hydrogrossular garnet? Gemstone Beach. Unpolished.
