September 2024 Stone Collecting Trip –Part 16, Back to Gemstone Beach, Sunday 22 September

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.

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.

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:

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:

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:

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:

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:

And this is a two-toned hydrogrossular garnet:

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