A Blog About Stone Gathering, Tumbling and Polishing, and Rocks and Landscapes, from New Zealand – With Musical Interludes (john.tumblestone@gmail.com)
F is for Fossil Rhodolith in Fossiliferous Limestone
Fossil rhodolith in limestone, Seadown Beach, Kakanui.
Other side of stone.
I found the stone above, as well as the one below, on a Kakanui (North Otago) beach in September/October 2024. They were identified for me by a fellow member of the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”who I met on the beach. The rhodoliths are the larger spherical features. Fossiliferous limestone is a type of limestone that contains noticeable quantities of tiny fossils or pieces of fossils – see Geology.com on the different types of limestone.
Another fossil rhodolith in limestone, Seadown Beach, Kakanui.
Other side of stone.
Rhodoliths are marine nodules of algae, made up mainly of calcium carbonate, that can grow to resemble beds of coral. They roll like tumbleweeds along the seafloor until they become too large in size to be moved by the waves and current. A field trip guide on Coastal Otago, written by Daphne Lee for the 2009 Geosciences Conference, describes the fossil rhodolith beds in the Kakanui area and the Waitaki Museum in Oamaru contains specimens of fossil rhodoliths – see page 12 here. For more, see “September 2024 Stone Collecting Trip –Part 24, Fossil Rhodoliths and Farewell to Kakanui’s Seadown Beach, Tuesday 1 October”.
Today was my last fossicking day on the south coast before heading back north. Chrissy and I had decided to visit Gemstone Beach this afternoon but the morning was so nice that we popped down to the beach in front of her home at Papatotara. It is on the Te Waewae Bay coast, some 30 kilometres by road to the west of Gemstone Beach. I had visited there a couple of times a week ago. We got to the beach at 10.45am and fossicked in an easterly direction, leaving one and three-quarters of an hour later. We took Ohla with us. I got a good photo of her before dirt got onto my camera lens, unnoticed, and ruined all but one of my other beach photos. I collected just over 30 stones. Chrissy found a nice large thulite which she generously gave to me.
Looking east on Papatotara beach.
Ohla enjoying herself.
My finds today plus Chrissy’s large thulite.
Chrissy’s thulite has gorgeous pink patches. Unfortunately, such stones don’t always tumble polish well.
Chrissy’s thulite find.
This black and white stone was my favourite find today – there’s a quality about the white in it that I find very interesting. But I don’t know what type of stone this is:
I picked up this next stone because its fragmented character makes for interesting patterns. It’s probably a mudstone of some kind, I think:
Two small stones, the first predominantly white but with a couple of black patches, the second being much darker but with some crystals that are likely to be translucent:
A nice trace fossil stone I found:
Trace fossil stone.
Other side of trace fossil stone.
I picked up one small trace fossil stone:
Finally, three more of my finds:
The next Post is about a possible application to “mine gemstones” from Gemstone Beach. The Post after that (not yet available) describes my second fossick of the day for 23 August, at Gemstone Beach, my last one there this trip. An Index to the Series is here.
The Index to Posts 1 to 7 can be found here, and for Posts 15 to 22 here. In this Index, you can click on a link to be taken to the relevant Post. The photos above each link give you an idea of some of the stones that feature in that Post.
*** ***
Wave moving up the Taunoa Stream, Gemstone Beach this morning.
Chrissy and Ohla and I arrived at Gemstone Beach at 3pm today, two hours before low tide. There were four other cars there when we arrived, relatively busy for a Thursday afternoon in winter. We forded the Taunoa Stream and made it down to the Waimeamea River, reaching there about 5pm before turning around. Ohla enjoyed the outing, and we enjoyed her company.
Ohla and Chrissy crossing the Taunoa Stream.
Ohla looking over the Waimeamea River.
Ohla at the break in the cliffs.
Gemstone Beach in front of the carpark today.
The Waimeamea River.
Returning to the Taunoa Stream.
The stones seemed to have been stirred up by the waves recently so that a good mix were on the surface. In places, the sand at the back of the beach had been piled higher. We found a few more trace fossil stones than in previous fossicks. I picked up a large banded argillite. Chrissy found quite a few small hydrogrossular garnets and one poppy jasper, the only one we saw during the afternoon. The sun was quite low by the time we got back to the carpark.
The low sun through the clouds.
Today’s finds.
The next day, Ohla was still taking it easy after her long walk.
I found a large but smooth stone that I thought Nicola from Hawkes Bay might like as she cuts stones – she will be coming down here in a few weeks’ time.
I picked up a small veined mudstone beacuse of the tiny fragment in the thickest vein on one side:
Small mudstone.
I really like the light blue hue of this type of stone often seen on Gemstone Beach:
A small find with some intense green in it:
Four others with green in them:
Chrissy’s very small poppy jasper…
Chrissy’s small poppy jasper.
…and my large banded argillite:
Banded argillite.
Four other finds:
Igneous stone.
Mudstone?
When I first saw this next stone, I wasn’t sure if maybe there were trace fossils in it. It seems to be an argillite that has been “baked” a little. The close-up photos confirm that traces are there:
Trace fossil stone.
Other side of trace fossil stone.
Four other stones with trace fossils showing the great variety that can be found:
This was my second-last fossick on Gemstone Beach this trip. It will soon be time to say good-bye to Chrissy and Mike and Ohla who have put up with me for three weeks.
Ohla and Chrissy making their way towards the Waimeamea River.
Ohla and Chrissy on the bank of the Waimeamea River.
Ohla, still resting up the next day.
The next Post in this Series is on a fossick on Papatotara Beach, featuring a large thulite found by Chrissy. The Index to the Series is here.
Seeking another break from working on images of stones and on blog posts led me to visit Bluecliffs Beach, just four kilometres west from where I am staying. I included a brief comment on this beach right at the end of a 2019 Post. As you move west along the Te Waewae Bay coast, the stones get bigger and bigger, and the stones on Bluecliffs Beach can be quite big! Many of the stones are over ten centimetres wide, some of them reaching 30 centimetres.
It was around noon when I drove across the new bridge over the Rowallan Burn and parked nearby. I walked 100 metres or so along a closed gravel road which had become a victim of the sea’s erosion, and then turned left onto the beach.It was cloudy, 11 degrees, and with a light breeze that wasn’t strong enough to deter a number of sandflies. There was a bank of large stones running for hundreds of metres along the shoreline, with sand at its base. The tide was high enough for waves to lap the bank from time to time. I walked for about 800 to 900 metres before turning around, a stroll over over two hours. I took photos of a number of the stones along the way, so this was primarily a photo fossick. But mostly I walked and enjoyed the quiet solitary wildness – it was just me, the stones, the waves and the bush. (And a few sandflies.)
Looking west along Bluecliffs Beach.
Bluecliffs Beach stones.
The bottom of the stone bank, Bluecliffs Beach.
Scattered stones on the sand.
Getting close to where I turned around.
Some of the smaller stones (2 to 6 cms) in the bank.
A couple of those sandflies.
Looking east on Bluecliffs Beach, with the Waiau River mouth about 8 kms away.
Most of the stones here seem to be granite, some quite light coloured, some with significant black in them, some orange/pink. There are a lot of varieties of quartz, some having feldspar patches.
Bluecliffs Beach stones.
Bluecliffs Beach stones.
But the stones that grab your attention first are the darker coloured ones with shell fossils in them:
The most impressive fossil rock I saw.
One of the smaller ones.
A bit of sand still on this fossil stone.
Another big one.
The beach features in “The Kiwi Fossil Hunter’s Handbook” under the heading of “Te Waewae Bay”. Below are the first four pages of the six-page entry. At least 40 different kinds of shell fossils have been found in the mudstones and sandstones of the Te Waewae Bay formation that is exposed in this area. These fossils are between four and five million years old.
Page 186 of “The Kiwi Fossil Hunter’s Handbook”
Page 187 of “The Kiwi Fossil Hunter’s Handbook”
Page 188 of “The Kiwi Fossil Hunter’s Handbook”
Page 189 of “The Kiwi Fossil Hunter’s Handbook”
“The Kiwi Fossil Hunter’s Handbook”
Ten of the stones I noticed in my walk – most of these are larger than 10 centimetres:
Interesting small smooth stones were few a far between but I did put nine in my bag:
The 9 stones I collected from Bluecliffs Beach.
Quartz.
Amygdaloidal stone.
Sugary quartz.
At the east end of the beach is Rowallan Burn. Its name was bestowed by the Scottish people who settled the southern part of New Zealand, the region south of the Waitaki River. For example, there is a Rowallan Castle southwest of Glasgow.
The bridge over the Rowallan Burn.
The Rowallan Burn running into the sea at Bluecliffs Beach.
Another Scottish name that occurs in the south, and much more often, is Iona. It is a name used for a wide range of features. For example, on my trips south, I regularly drive past Camp Iona in Herbert, North Otago, a facility owned by the Presbyterian Church. Port Calmers’ Iona Presbyterian Church was the second church to be built in Otago, the third in the South Island.There’s an Iona Island near Half Moon Bay in Rakiura Stewart Island. Gore’s Peacehaven Retirement Village’s dementia care unit is called Iona. Many towns and cities in the south have streets named Iona. I have also seen a number of private houses with “Iona” on them. This song by The Waterboys is about the Scottish island of Iona, but it echoes aspects of Bluecliffs Beach, especially what I experienced as the “peace of the stones”:
“Peace of Iona” by The Waterboys (2003)
Peace of the glancing dancing waves Peace of the white sands Peace of Iona Peace of the singing wind Peace of the stones Peace of Iona I-i-i-i-i-i-i-i-i-i-i-i-i-i ona
Peace of the crying gulls Peace of the humming bees Peace of the noon-time stillness Peace of the dreaming hills Peace of the breath of angels Peace of Iona I-i-i-i-i-i-i-i-i-i-i-i-i-i ona
Peace of the saints and seekers Peace of the monks and Druids Peace of the resting place of kings Peace of the ruins Peace of the doves in the bell tower Peace of Iona I-i-i-i-i-i-i-i-i-i-i-i-i-i ona
Peace of the rested mind Peace of the glad heart Peace of my lover’s pots and potions Peace of her healing hands Peace of her lazy laughter Peace of Iona I-i-i-i-i-i-i-i-i-i-i-i-i-i ona
The tiny island of Iona sits off the west coast of the Isle of Mull in the Highlands of Scotland. It’s just five kilometres long and one and a half kilometres wide. It’s known as Scotland’s sacred isle. An abbey was founded there in 563 by the monk Columba who spread the Christian faith to most of Scotland and northern England (the Presbyterian Church has a Camp Columba at Pukerau, near Gore – I attended a number of Easter Camps there when of high school age). The famous “Book of Kells”, a lavishly illustrated set of the four Gospels, was produced by Iona monks from 800 on. This centre for learning and worship became a place of pilgrimage and even of political significance – it is said that 48 Scottish kings are buried there. Mike Scott of The Waterboys visited Iona a number of times – for a period he was living at the Findhorn Foundation Community which had a retreat house on the island (see YouTube video above). His stay there in 1994 inspired him to write “Peace of Iona”. Iona and Bluecliffs Beach are completely different places – but the peace of the stones is common to both.
The next Post in this Series describes a three hour fossick on Gemstone Beach, my second-last visit there for this trip. An Index to the Series is here.
It’s been a few days since my last fossick at Gemstone Beach. On Friday and Saturday, I had visited a beach closer to where I was staying. On Sunday, it was cold and wet and windy so I stayed inside. I decided to be brave and venture out today. In the morning, it was cold and wet and windy but the weather forecast looked promising for the afternoon – I use a weather forecaster called “Yr.no” and it provides hour by hour forecasting that I generally find very useful. “Yr.no” is a popular, publicly-funded Norwegian weather service that provides surprisingly detailed weather forecasts worldwide through its website and mobile app.”Yr” means drizzle in Norwegian. The service is jointly produced by the Norwegian Broadcasting Corporation and the Norwegian Meteorological Institute.
“Yr” map for southern coast of South Island, New Zealand. Note: Wind is in metres/second.
“Yr” forecast page for Orepuki. Note: Wind is in metres/second.
“Yr” forecast for Orepuki today, hour by hour. Note: Wind is in metres/second.
I arrived at Gemstone Beach at 11.40am – it was an outgoing tide with low tide due at 2.00pm. The temperature was only six degrees, but at least the rain stopped when I arrived. Initially there was very little wind but halfway through my fossick, , a bitterly cold breeze sprung up, stinging any exposed skin. Despite the dark day, one carload of what was probably a Mum and Dad with a young child were there when I pulled up, and even more people arrived after that. The Taunoa Stream was running too high and fast to cross, due to the rain over the last day and a half, so I spent just over an hour fossicking back and forth a couple of times on the beach in front of carpark. The temperature had risen to nine degrees when I left at 1pm.I found one small but kind of different poppy jasper and only one small hydrogrossular garnet but a number of interesting looking stones.
Arriving at Gemstone Beach on a cold wet day just before noon.
The family that was on the beach when I arrived.
Others arrived while I was there.
The Taunoa Stream, too fast and deep to cross today.
My finds today.
Gemstone Beach stones near the Taunoa Stream.
Gemstone Beach stones near the Taunoa Stream.
Gemstone Beach stones near the Taunoa Stream.
The small poppy jasper I found today was interesting because the orbs were spaced apart, not crowded together as is more usual:
One side of the small poppy jasper.
Other side of the small poppy
An intense green stone with lots of little bits in it:
The purple hues and white shapes in this stone caught my eye:
I like the dark stones with white crystals or spots. In the first side of this stone, the regular white spots are interrupted, are smaller and fainter:
I have found lots and lots of breccia stones on Gemstone Beach, where the fragments (“clasts) in the stone are angular (see this Post from September last year, for example). Conglomerates contain rounded fragments, and I have been looking for specimens without success until maybe today. The larger fragments in this stone are rounded, although some the tiny fragments are angular:
Sometimes a stone may not be purely a breccia or conglomerate but may contain both angular and rounded clasts. I’ve been trying to think of a good name for such but have not yet thought up one.
A partly brecciated stone, with tiny angular fragments:
I picked up this trace fossil stone because of the way some of the traces seemed to radiate from a central point, an unusual pattern:
Normally I tend to collect protovirgularia traces – lines of chevrons – but there are a wide range of other types of traces. A well-illustrated account of the different types of trace fossils can be found in this Sedimentary Geology textbook.
Looking east, towards Gemstone Beach 15 kilometres away.
I’m staying at Chrissy and Mike’s place at Papatotara, 34 kilometres by road via Tuatapere from Gemstone Beach, 15 kilometres along the coast as the karoro (black-backed seagull) flies. The beach here, on Te Waewae Bay, is west of the Waiau River, with Gemstone Beach being east of the river. Chrissy has featured some of the stones she has found on this beach in her Tumble and Polish Blog. She made these observations: “Whilst not as smooth as its Gemstone Beach counterparts, there’s always the odd stunner that catches my eye. Theses stones often need a few tumbles/redos in Stage 1 because they are a lot rougher. There is a lot of granite down here too and that particular stone doesn’t tumble too well.”
After doing some blogging on Friday morning, I decided to take a break and go to the beach. This involved a 12 minute walk across a couple of paddocks, through some muddy patches, and down a steep track. I arrived on the beach at 12.55pm during a low tide. It was sunny with a light breeze. I fossicked eastwards for more than an hour then turned around and fossicked back to the beach entrance. I left at 2.40pm with about 40 finds. For the first time this trip, sandflies appeared and I had to put my hands in my pockets to avoid their bites.
The turnoff from the Papatotara Coast Road.
There is a parking area down this road.
The beginning of the walk across the paddocks.
The mountains to the west.
The top of the muddy track down to the beach.
At the bottom of the steep muddy track, looking over Te Waewae Bay.
Looking east, towards Gemstone Beach 15 kilometres away.
Looking west on the beach.
Papatotara Beach stones.
Papatotara Beach stones.
Starting back up the steep muddy track.
Friday’s finds, Papatotara, Te Waewae Bay.
I found a very nice green hydrogrossular garnet, half buried in the sand near the beach entrance. This is the furthest west on Te Waewae Bay that I have found one. It is also among the best half dozen garnets I have found. Its green colour is the classic gooseberry-green hue of a hydrogrossular, and is a deeper green than most specimens. Corina, a local fossicker, told me a couple of days ago that old-timers used to find green ones a lot more than are found currently. In February 2024, I was shown an even better green one found by Vern on Gemstone Beach. My find today (Friday) is a nice size with some heft to it. Here are photos of it dry:
Hydrogrossular garnet, dry.
Other side of hydrogrossular garnet, dry.
And here are photos of it wet, as well as with a torch behind it:
Hydrogrossular garnet, wet.
Hydrogrossular garnet with torch behind it.
As Pink Floyd puts it, “In the shadow of the wave…, green is the colour of her kind”. They were singing, at one level, about the green island of Ibiza, part of the Spanish Mediterranean, which they were visiting to record an album. But green is also the colour of hydrogrossular kind.
“Green is the Colour” by Pink Floyd (1969)
Heavy hung the canopy of blue Shade my eyes and I can see you White is the light that shines through the dress that you wore
She lay in the shadow of the wave Hazy were the visions of her playing Sunlight on her eyes but moonshine made her cry every time
Green is the colour of her kind Quickness of the eye deceives the mind Envy is the bond between the hopeful and the damned
Chrissy has told me that she has found a good-sized poppy jasper on this beach. Today (Friday) I found three small specimens:
I spotted a small pink thulite stone, and a larger banded argillite:
Small thulite.
Banded argillite.
Four more Friday finds:
The only other hydrogrossular garnet I found.
Some green epidote and orange feldspar in this stone.
Amygdaloidal stone.
Quartzy with a little epidote.
The next day, Saturday, I spotted a whale out in Te Waewae Bay, in front of my accommodation. For quite some time, it was lifting its tail out of the water then slapping it back down:
I noticed a white area in the blue…
It turned out to be a whale, tail first.
Not long after, I returned to the same beach I had visited on Friday, this time walking westwards, the opposite direction. I spent two hours there. The tide was a little lower and less stones were wet. At one point, two horses and riders loomed out of the distance in front of me.
Less wet stones today, Saturday.
Two horses and riders in the distance.
Saturday’s finds.
I found fewer stones than Friday, no hydrogrossular garnets, but two poppy jaspers, one very small.
A couple of interesting green stones:
Two black and white stones:
Feldspar crystals?
Less well defined white features.
Four final Saturday finds:
The next Post in this Series takes us to Gemstone Beach again. An Index to the Series is here.
This is my fifth contribution to the current Alphabetical Series in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. In the 2021 version of this Series I posted “E is for Entrance”(an “entrance” allows you to “look into” a stone, to see beyond its surface).
E is for Epidote
Quartz-veined Gemstone Beach quartzite with epidote.
Other side of veined quartzite.
Epidote is a green mineral. I found this quartz-veined green quartzite on Gemstone Beach about 18 months ago – see “A Red, a Green and a Pink, Gemstone Beach, Wednesday 21 February 2024”. Its green is due to epidote. Epidote is also in many argillite stones on Gemstone Beach. When epidote is present in a rock, it causes it to have a green to yellow-green (pistachio-like) colour, sometimes quite deep and intense. It was named in 1801 by French mineralogist René Just Haüy (known as the Father of Modern Crystallography) from the Greek “epidosis” meaning “increase”, because the base of its rhombohedral crystal prism has one side larger than the other. For more, see Geology.com.
Stones at the foot of the cliff at the beack of the beach.
This morning’s two and a half hours fossick began at low tide. It was another cool sunny day without wind, very comfortable for stone hunting as I was wearing a puffer jacket and woollen hat and scarf. I noted the presence of four other serious fossickers there at different times, plus some passing motorists. I spent part of my fossick looking at the stones which had accumulated at the foot of the cliffs which back the beach. When I departed at 12.15pm, there were eight other vehicles in the carpark.
Looking east over the Taunoa Stream towards the beach in front of the carpark.
The Taunoa Stream.
Looking west.
Stones at the foot of the cliff at the beack of the beach.
Gemstone Beach stones.
Gemstone Beach stones.
The first of today’s featured finds caught my eye because of the small circular features in it:
I like the texture of this stone:
One side of stone.
Other side of stone.
There are some interesting tiny veins in this small find:
Two different poppy jaspers, with two sides of the second one shown:
First poppy jasper
Second poppy jasper, side 1.
Second poppy jasper, side 2.
An amygdaloidal stone, a stone with many tiny vesicles (gas holes) that have been infilled with minerals:
Amygdaloidal stone.
An argillite stone with dark trace fossils in it:
Trace fossils are not fossils of an animal but are fossils of the traces they leave behind. “Trace fossils are what is left of the activity of some ancient critter”, writes retired kiwi geologist Brian Ricketts in his blog “Geological Digressions”. That activity includes burrowing, moving, excreting, fighting and feeding.
Finally, two hydrogrossular garnet finds:
Hydrogrossular garnet.
Stone with hydrogrossular garnet in it.
As I note in a detailed Post on them, hydrogrossular garnets are not like the garnets we know as precious gems – they come from dense rock masses, not crystals. Technically, hydrogrossular garnets are a calcium aluminium garnet with hydroxide partially replacing the silica found in other garnets. The first ever identification of hydrogrossular garnet in the world was in 1943 by Colin Hutton, from stones found in Nelson, and it is the most widely spread of the 13 minerals first described from New Zealand. More details can be found in “First Identified in New Zealand in 1943 – Revisiting the Hydrogrossular Garnets of Gemstone Beach, February 2023”.
The evening after this fossick I drove to Invercargill to attend the monthly meeting of the Southland Geological and Lapidary Club. Around 15 or 16 others were there. Guest speaker was Lloyd Esler, a well-known Southland historian and teacher. He handed around about 20 rocks, fossils and artefacts, and talked about them. One was a ventifact, a stone shaped by wind-driven sand. Another was fulgurite, created when sand gets fused together by a lightning strike. From Gemstone Beach, there was a trace fossil stone and some vivianite, a blue mineral associated with decaying organic matter – this was from the peat layer in the Gemstone Beach cliffs. Then there was a container of volcanic ash, very fine and abrasive. Lloyd mentioned how flying through a volcanic cloud had once shut down a passenger airplane’s engines. I remembered this incident from my viewing of the excellent air crash investigation documentaries so I hunted it down on YouTube. Here is the episode about that 1982 747 flight:
The next Post in this Series covers two fossicks on a Te Waewae Bay beach at Papatotara.An Index to the Series is here.
Corina lives just outside of Orepuki, a couple of kilometres from Gemstone Beach. I had previously messaged her a few times about the stones of Gemstone Beach as she is a member of the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. I then met Corina briefly on the beach during a fossick with Chrissy in September 2024. She mentioned that she had once found three small sapphires which she had donated to the Riverton Museum (see photo below, left). An old Gemstone Beach Hertiage Trails sign (photo below, centre) mentioned sapphires, as does page 8 of Jocelyn Thornton’s “Gemstones” (see photo below, right). In June 2019, I wote a Blog Post titled “The Elusive Sapphire of Gemstone Beach”. Chrissy and I are now working on a photo book about Gemstone Beach stones, using photos of stones we have found. However, we have not found a Gemstone Beach sapphire so I have been hunting out photos of other people’s finds. I messaged Corina a month ago to confirm that the three stones in the museum had been found by her. She mentioned she had another one still in her possession. She happily agreed I could photograph it when I was in Southland this month.
Corina is fascinated by stones and she has collected specimens from a number of places, not just Gemstone Beach. Although she has a lot from Gemstone Beach! When I visited her four days ago, I took photos of four of her stones. The first was a small sapphire, the size of my thumbnail. It is dark blue and recognisably a Gemstone Beach sapphire with its rich deep blue colour:
One side of the sapphire, dry.
Other side of the dry sapphire.
The wet sapphire.
When I wet the stone (see third row of photos above) the water moved off it quite quickly. This is a characteristic of hydrogrossular garnet. Interestingly, the photo of a Gemstone Beach sapphire on the website of the Otago Rock and Mineral Club states that “The blue colour is sapphire which is combined within the structure of a hydrogrossular garnet”.
Corina showed me two other small stones with a little bit of blue in them which is also likely to be inside hydrogrossular garnet. This is the first:
One side of stone.
Other side of stone.
The second has a faint pink tinge:
One side of stone.
Other side of stone.
The fourth find that Corina showed me was one from the day she met Chrissy and me on the beach. It is very black, and is highly likely to be a hydrogrossular garnet – it has a very smooth, slightly waxy feel. Black is a very unusual colour for this type of stone:
Black hydrogrossular garnet.
I am grateful to Corina for letting me take these photos and use them on TumbleStone Blog.
