Month: September 2024

Petrified wood, Gemstone Beach.

Gemstone Beach.

Today was a relatively fine day, though cool. I spent four hours on Gemstone Beach, walking down past the Waimeamea River lagoon. The tide was low and the sun came out for some of the time. I had a chat with the local gold miner down the beach, and later also met Paul near the lagoon – he was looking for hydrogrossular garnets. There were two other serious fossickers I passed on my way back to the carpark.

Taunoa Stream in foreground, looking towards the Gemstone Beach carpark.

Gemstone Beach.

Gemstone Beach stones.

[The weather was cloudy for a number of days after this fossick and it has been difficult to get good photos of stones – low light conditions means that wet stones get a lot of reflections on them. You will note this issue in some of the photos below.]

For the first time I found a piece of petrified wood on Gemstone Beach. I have a couple of pieces that were given to me by someone who fossicked on the beach some decades ago (see this Post), but am not aware of recent finds. The piece I found is four centimetres long:

Petrified wood, Gemstone Beach.

Other side of the petrified wood.

Another side of the petrified wood.

Petrified wood viewed from the “end”.

The pink in this stone caught my eye:

Other side of stone.

The next stone has a lot of pistachio-hued green in it, typical of the mineral epidote. But there’s a lot more going on in it – a complexity of composition:

Other side of stone.

Another epidote-green stone, this time with a very large quartz vein in it:

Large quartz vein.

A breccia with many different types of fragments in it:

A small dark stone with a fascinating composition:

An even smaller stone, a hematite jasper with some fire in it:

Very small hematite jasper.

An amygdaloidal stone – the photo doesn’t do it justice (due to light conditions affecting sharpness and colour):

Amygdaloidal stone.

A small brecciated jasper?

And, finally, two trace fossil stones to add to the great diversity I have collected of this type:

Busy trace fossil stone.

Gray trace fossil stone.

Part 19 is a fossick at a Riverton Aparima beach. The Index to the Posts in this Series can be found here.

A wide shallow seepage from the Waimeamea River lagoon.

Another three hour fossick on Gemstone Beach this morning. Tomorrow is going to be stormy so I wanted to go out there today. I have just five more days down here before I drive north again. The tide was low and I walked over a kilometre to the mouth of the Waimeamea River. Usually I turn around at that point but today I decided to go just a little further – and after about 100 metres I found today’s one and only poppy jasper!

Small poppy (orbicular) jasper.

I picked up more hydrogrossular garnets than usual (some of them are featured at the end of this Post), and found some interesting bright stones. The Waimeamea River was still not flowing across the beach, being held back by a mass of stones dumped by the sea. There were four or five large seepages as water flowed under the stones from the lagoon, and there was good fossicking in and near those.

Gemstone Beach near the Waimeamea River, looking west.

Gemstone Beach near the Waimeamea River, looking east. Local gold miner and his dog and quad bike in middle distance.

A wide shallow seepage from the Waimeamea River lagoon.

The shallow seepage of water through stones, Waimeamea Lagoon.

The edge of a deeper seepage – side channels.

This morning’s finds from Gemstone Beach.

Maybe the brightest of my finds is this green stone with light squiggles:

The brightest of this morning’s red stones, with bright oranges swirls:

An amygdaloidal stone (infilled volcanic bubbles), with bright and colourful amygdales and a fine deep purple vein:

Amygdaloidal stone.

A small rhyolite with some bright red in it:

Gemstone Beach rhyolite.

I also found some stones with interesting patterns. My eye was initially drawn to the tiny black lines in this stone:

Gemstone Beach stone.

Other side of stone.

Another patterned stone, with different coloured minerals in white quartz:

A type of “cloudy” quartz stone:

One of my larger finds, six centimetres long, packed full of interestingly shaped crystals (probably plagioclase feldspar):

Two of the trace fossil stones I found today, one green, the other gray:

Finally, six of my hydrogrossular garnets from this morning. The first has some intense green mineral inclusions:

Hydrogrossular garnet.

The second has a pink blush that in reality is greater than captured by the camera:

Hydrogrossular garnet.

An intense yellow:

Hydrogrossular garnet.

A lighter yellow garnet with some patterning inside it:

Hydrogrossular garnet.

A white specimen with an interesting vein:

Hydrogrossular garnet.

Finally, a hydrogrossular garnet that has a smooth end and a very rough non-shiny end, confirming the wide range of of its expression:

Hydrogrossular garnet.

Part 18 records the rare discovery of petrified wood on Gemstone Beach. The Index to the Posts in this Series can be found here.

Before long, a few more people arrived.

I arrived at Gemstone Beach this morning at 9.20 am, at low tide, just before about three or four carloads of other people arrived. Before that, I could see just two fossickers away in the distance, on the other side of the Taunoa Stream. Then Chrissy, (who writes the Tumble and Polish Blog) texted me to say she had decided to come down too. While waiting for her, I fossicked along the beach in front of the carpark and then walked up the Taunoa Stream. There, I was approached by two young people asking what I was looking for. They were from overseas and spending a few weeks in the South Island. I showed them some of the stones I had just picked up, including a trace fossil one and and an amygdaloidal one, and talked about their origin. I don’t always take polished stones with me to the beach but I did today, so I was able to show the young couple the difference that polishing makes. I gave them a polished amygdaloidal one to take away with them – it is the stone that features in the Post “A is for Amygdaloidal”.

The Taunoa Stream was easier to ford today than the last time we visited here. Once across, Chrissy and I discovered that one of the fossickers there was Corina, a local who often looks for stones on the beach. She is a fellow member of the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. She and I had messaged a few times about Gemstone Beach and its stones but not met in person. Until now. She showed us some of her very interesting finds.

Upon my arrival, just two distant fossickers could be seen on Gemstone Beach.

Before long, a few more people arrived.

A passing motorist on the bank of the Taunoa Stream.

Corina on the other side of the Taunoa Stream.

Chrissy and I then moved down to the Waimeamea River. The breeze was cool and the morning was cloudy until the sun came out just as we turned around. We eventually made it back to the carpark at 1 pm, just after a small rain shower passed over. Chrissy found a small poppy jasper and a few hydrogrossular garnets, including a large specimen of what I have called the fifth type (white with dark diopside inclusions) – see the TumbleStone Two Post “Hydrogrossular Garnet”. I found a large specimen of the sixth type, what I call the “porcelain” type, an opaque stone that looks and feels like porcelain china, often having fine blue-green veins. I have some good examples of these so I left my find with Chrissy, for her rock garden.

Chrissy on Gemstone Beach.

Chrissy fossicking where the water from the Waimeamea Lagoon emerged from the stones.

Waimeamea Lagoon, held back by a bank of stones but seeping to the sea through them.

Chrissy’s poppy jasper find.

The large porcelain-type hydrogossular garnet I found that I left with Chrissy.

Among my finds today was this small stone. I could see some interesting detail in it and it proved intriguing to see what the photo revealed:

Small Gemstone Beach stone.

Bright red stones are always worth picking up and examining closely. Following are four of my red finds today. The first one is a bit different from the usual bright red jasper, being darker and more orange. On the beach, the coloured area seemed rather blurry but the photo shows some orb-like composition:

I did find a very small “normal” poppy jasper, just under two centimetres long, maybe half the size of Chrissy’s find:

Very small poppy jasper.

The next red stone is maybe a quartz with some moss-like iron oxide in it. I question whether it is a jasper partly because of how quartz is present and the way the mossy mineral looks “dirty”:

The white quartz veins of the next small red stone initially caught my eye but it was the green and purple veins I then saw that meant I had no hesitation in putting it in my bag:

This one is more purple than red to my eye (people vary in their colour perception), and has a lot of quartz in it:

The thin green vein in this light-orange coloured stone caught my eye. I assume the presence of alkali feldspar (also called potassium feldspar or K-feldspar) gives the stone its orange hue, while the green vein is most likely to be epidote:

Five of my green finds follow. The first is particularly bright:

A very small green breccia that I find fascinating:

The next one is probably argillite, a very common stone on Gemstone Beach. Argillite is a hardened mudstone, and its green colour is usually due to epidote. Orepuki is mentioned as a locale for epidote in Mindat. The small circular features in this stone caught my eye:

Green argillite is also the host rock for many of the trace fossils to be found on Gemstone Beach. This one is interesting because of the lighter green of the traces:

Trace fossils in argillite.

One of the first stones I found, in front of the carpark while waiting for Chrissy, was this trace fossil one – the green of the stone is different from the previous stone, and the colour of the trace fossils is also quite different:

Trace fossils in argillite.

I collected a handful of small hydrogrossular garnets today, and two of them finish off this Post. This one has interesting veins and fragmentation in it:

Small hydrogrossular garnet.

And this is a two-toned hydrogrossular garnet:

Small two-toned hydrogrossular garnet.

Part 17 is here. The Index to the Posts in this Series can be found here.

Chrissy and Ohla this morning – prepared for the weather to take a turn for the worse.

I arrived at Gemstone Beach at 9.30 a.m., just before Chrissy drove into the carpark. Along with her lovely dog Ohla, we spent 90 minutes fossicking on the beach, and I collected 55 stones. High tide was to be at 1 p.m. but when we left at 11 a.m. the waves were starting to sweep right up the beach. Upon arrival, the temperature was 12 degrees and there was little wind. We forded the Taunoa Stream and spent most of our time fossicking for about 300 metres past the stream.

Looking back towards the carpark from 100 metres past the Taunoa Stream.

The waves and stones of Gemstone Beach.

Chrissy and Ohla this morning – prepared for the weather to take a turn for the worse.

One dog and many stones, Gemstone Beach.

On our way back, just as we reached the stream, the wind came up, the hail came down, and the temperature plunged to six degrees. It became distinctly uncomfortable. Luckily, we were not far from our vehicles!

Thirteen of my morning’s finds are featured below. The first is the most intriguing, maybe a breccia of many tiny fragments:

Gemstone Beach stone.

A bright little stone, what I think could also be a breccia where the white clasts are partly in a yellowish matrix:

Small breccia.

Other side of small breccia.

I found a few good trace fossil stones this morning. Here are three which illustrate their diversity: different colours, different arrangements, different degrees of completeness:

Hard-to-see trace fossils.

Long trace fossils.

Trace fossil hints.

I also picked up a handful of nice hydrogrossular garnets. These are the three best, in descending order by size (6.5 cms long, 4 cms, and 3 cms):

Hydrogrossular garnet.

Hydrogrossular garnet.

Hydrogrossular garnet.

A dark-coloured brecciated hematite jasper with a little quartz in it:

Gemstone Beach jasper.

Other side of Gemstone Beach jasper.

When I found this jasper on the beach, I thought it was likely to also be brecciated but I can now see there is a hint of the orbicular in it too:

Some orbicular features in this jasper.

Two different veined greenish quartzites:

And finally, another stone with an intricate tracery of veins:

Part 15 involves a visit to a Slope Point beach. The Index to the Posts in this Series can be found here.

Driftwood on Gemstone Beach.

Yesterday was another cold wet one so I stayed inside. This morning, I had itchy feet so I visited Gemstone Beach at a time when the forecast suggested the weather would be best. I arrived there just after 9am, with high tide due around noon. I realised it wouldn’t be safe to venture over the Taunoa Stream, with the waves coming progressively higher up the beach, so I knew I would be spending my time on the 200 to 300 metres of beach in front of the carpark. During the 80 minutes I was there, it was 10 degrees with a chilly though light wind, and with only a sprinkling or two of rain. I was able to wield my camera today, unlike my last fossick here.

There is a small stream just to the east of the carpark – it is not named on any map I have seen so I have christened it The Stream With No Name. A large area of stones has been moved by the sea to the east of that stream. These stones weren’t there two days ago, and they proved worthy of a good fossick before I moved westwards to the Taunoa Stream.

Looking over The Stream With No Name.

The fresh stones just past The Stream With No Name.

Distant snowy mountains to the west.

Gemstone Beach scene this morning.

Driftwood on Gemstone Beach.

The Taunoa Stream, running high.

The Taunoa Stream has been running hard up against the cliff and brought some of it down.

I spent 80 minutes on the beach, collecting 60 stones, 14 of which are featured below. I saw only two passing motorists briefly venturing down towards the end of that time. They were chased up The Stream With No Name by an incoming wave and likely decided it was safer and warmer in their vehicle.

Gemstone Beach stones.

The Stream With No Name.

A wave moving up the Stream With No Name.

I spotted this small dark stone right next to the Taunoa Stream. I could see there was something going on in it, but I needed to see the close-up photos to work out its brecciated character.

Small dark brecciated stone.

Other side of small dark brecciated stone.

In “breccia”, the fragments (or “clasts”) that make up the stone have not travelled far before being cemented together and so are angular and sharp. In a “conglomerate”, the fragments have undergone some rounding from the travel they have experienced, usually from water, prior to being cemented together. For some information on brecciated stones and Gemstone Beach, see “January 2022, Stone of the Day #2 – Breccia and the Giant Landslides of Fiordland”. ThoughtCo has a good article on breccia. Sometimes, a brecciated stone is caused when massive stresses on a rock tears fragments from it which are then cemented in a matrix – this is often known as “tectonic” breccia. Other times, “sedimentary” breccia occurs, when fragments from different stones end up cemented together in a fine-grained matrix. A third main type is “igneous” breccia. A breccia where the fragments represent more than one rock type is called “polymictic” while one where the fragments come from just one rock type is termed “monomictic” (University of Auckland Geology). I would guess that the small dark stone I found is a monomictic sedimentary breccia of maybe mudstone clasts. There seems to be a little quartz and green epidote in it as well.

I suspect the following two stones I also found this morning are “monomictic sedimentary breccia of mudstone clasts” as well. The second appears to be a “dirtier” version of the first:

Breccia stone.

Another breccia stone.

Three of my other interesting finds this morning are an amazing mossy jasper, a pastel blue/green quartzite with intriguing depths, and a small pink stone with large areas of black:

Mossy jasper.

Other side of mossy jasper.

Brecciated and veined quartzite.

Other side of quartzite.

Gemstone Beach pinky.

Other side of pinky.

The best areas to find hydrogrossular garnets are a few hundred metres west of the Taunoa Stream but it is also possible to find a specimen or two in front of the carpark. I found this one just three minutes into my fossick:

Small hydrogrossular garnet.

Other side of hydrogrossular garnet.

Trace fossil argillite stones are more common right along the beach, and can also be found as far as Riverton Aparima over 30 kms to the east (and far beyond). This morning, I found a handful of them during the last ten minutes of my fossick, while walking up The Stream With No Name. Here are four of them, including a larger stone which is destined for the rock garden at home.

Trace fossils.

Trace fossils.

Trace fossils (in gray).

Large trace fossil stone (9 cms long).

Circles and dots in a stone always attract my eye. But in the case of the next find, I actually spotted the linear squiggles side on the beach and only noticed the dots when turning the stone over:

The circular features of spotted argillite are always interesting to me:

Spotted argillite.

Gemstone Beach’s spotted argillites come in a wide range of colours. Sometimes the spots are darker than the rest of the stone, sometimes lighter. Sometimes the spots are circular, sometimes more “deformed”. I provide 12 varieties of spotted argillite in this Post – see Stones Gn20 to Gn31. There I suggest that such spots occur when argillite comes under increased pressure and heat, more than is usual for a sedimentary rock. Certain minerals then become concentrated in specific areas.

The final stone I picked up this morning, lying in The Stream With No Name, is this igneous one. Ten centimetres long and a fine specimen of a type of stone that can be found on Gemstone Beach, it is destined for the rock garden,

Large igneous stone, 10 cms long.

Part 14 is another Gemstone Beach fossick. The Index to the Posts in this Series can be found here.

Following my morning fossick at the Back Beach, I let fellow fossicker Chrissy know I was going to check out Gemstone Beach in the afternoon. But I warned her that the beach’s Taunoa Stream might not be fordable and that the forecast was for rain and low temperatures. There was a sprinkling of snow on the tops of the Longwood Range, and the Eastern Fiordland mountains had significant snow cover. However, Chrissy was not deterred, so we met in the Gemstone Beach carpark at 1.30pm, about 90 minutes after high tide. It was cold – nine degrees with a wind, and it started raining shortly into the fossick. As a result, it became bitterly cold and our hands and faces suffered. But we made it over the Taunoa Stream without getting wet gumboots, thanks to both of us wearing waterproof over-trousers.

The rain meant that all the stones on the beach were wet. So we could easily fossick all over, wherever there were stones. And we found a great diversity of very interesting stones. Despite the chilly conditions, we made it down close to the Waimeamea River mouth before turning back. Turning around meant that we turned our backs to the direction from which the wind and rain was coming, a welcome relief. We got back to the carpark just under three hours after setting out. Our backpacks were heavy.

I left my camera in my backpack because of the rain and cold. So I have no photos of the beach from this afternoon. And I couldn’t take photos of the stones until the next day. The next day was also wet and cold, but a couple of brief patches of sunshine in the morning allowed me to snap some images for this Post. It was difficult to select the stones for the Post, given the large number of very interesting finds. I have managed to whittle them down to 18. I took photos of only one side of many of the stones because of time constraints, though two of them had such interesting fronts and backs that I took photos of two sides.

The first double-sided stone is a gorgeous small jasper, only 2 cms long. The white in it stood out on the beach:

Small jasper, Gemstone Beach.

Other side of small jasper.

The second double-sided stone is also small, 3.5 cms long, a yellow quartzite with some brecciation:

Small quartzite, Gemstone Beach.

Other side of small quartzite.

The three largest stones featured in this Post are all 5 cms long: maybe what is a pale brecciated quartzite, a veined jasper, and a predominantly white volcanic stone:

Only one poppy jasper was found this afternoon, by me about halfway back to the carpark. Below it is another interesting jasper I found and a quartz with iron oxide through it:

Poppy jasper with tiny orbs.

Jasper and quartz?

Likely to be quartz.

The diversity of stones on Gemstone Beach is remarkable, and I always come across types of stones I have not seen before, some with amazing colours and patterns inside them. Some of the patterns can be subtle and delicate, and appear only upon close inspection:

Three more of my finds:

Stone with thin veins and tiny fragmentation.

Once again, Chrissy found more hydrogrossular garnets than I did (not that it’s a competition). However, below are three interesting ones I put in my bag:

Hydrogrossular garnet.

Hydrogrossular garnet.

Hydrogrossular garnet.

Information on the different types of Gemstone Beach hydrogrossular garnets can be found here.

In Part 13, I return to Gemstone Beach for an 80 minute fossick at high tide, collecting 60 more stones for tumble polishing. The Post also contains information on breccia. The Index to the first ten Posts in this Series can be found here.