My first fossick on Gemstone Beach (Southland) this trip was with Chrissy and Ohla the dog. We arrived a couple of hours after high tide, at 2.10pm, and left two and a half hours later. It was a sunny winter afternoon, the temperature was 10 degrees with a very light breeze. I wore a puffer jacket, woollen hat and scarf, and was very comfortable throughout. There were four vehicles in the carpark when we got there, one a camper van.
Recent comments on social media have noted that over the last few months there’s been a lot of sand and not many stones on Gemstone Beach. That is still the case, in the main. We found that there were very few stones for the first 150 metres between the carpark and the Taunoa Stream, much of this area being completely bare sand. Then we encountered a 25 metre-wide patch of stones. A further section of sand, maybe 60 to 70 metres long, took us to a 25 metre band of stones running along the edge of the Taunoa Stream.
The Taunoa Stream was running directly across the beach to the sea – it usually wanders a bit before getting there. Crossing was easy as even though the flow was fast, it was shallow. Walking northwest, the beach continued to be covered in stones for another 130 metres or so before the sand took over again.
From the Taunoa Stream to the Waimeamea River, sand dominated the beach apart from three large patches of stones. The first one (30 metres wide) was located about 150 metres along, the second one (maybe 35 metres wide) was a further 120 metres down the beach – it contained some larger stones (up to 12 cms) among the smaller ones. Just 15 metres on was the third patch 0f stones (20 metres wide) and then a long sandy stretch that could be 400 metres long, taking us to the start of the Waimeamea River lagoon (the first half of it dry and full of driftwood). A good patch of stones of maybe 250 metres then took us to the Waimeamea River itself. It was just possible to ford the river without taking our gumboots off. On the other side, continuous banks of stones stretched into the distance.
As is often the case with my first fossicks on Gemstone Beach after being away for a while, I didn’t find a lot of outstanding interesting stones to put in my bag. It usually takes me two or three fossicks to get my eye used to the process of spotting really good ones. However, the low mid-winter sun and the shadows it cast among the stones didn’t help either! I saw very few hydrogrossular garnets though Chrissy spotted more, even one that I walked right past! She also found an interesting raised trace fossil stone that she kindly gave to me (photo below). I picked up one tiny jasper that could be a poppy. Among the more interesting stones were a number of breccia of different characters, and a small pink stone. Again as I usually do with a first fossick, I picked up a range of stones of types that I might not bother with in later fossicks. Altogether, I came away with about 75 finds, 14 of which are featured in this Post.
A breccia stone consists of angular non-rounded fragments, sometimes from different sources, cemented together in a fine-grained matrix. Following are four of the breccia I collected this afternoon. The first contains a diverse mix of fragments from different sources, making it a polymictic breccia. Some of the fragments are themselves quite complex in their composition:
This second one is also polymictic:
A third breccia in which the fragments are more uniform, likely all coming from the type of rock, making this a monomictic breccia:
The fourth and final breccia is distinctly monomictic, looking like it consists entirely of mudstone (argillite?) fragments:
This is the unusual very small pink stone I found – it has a tiny white spot on one side and a tiny white patch outlined in dark red on the other:
Thulite and rhodonite, both being types of pink stones, are found on Gemstone Beach. This find is more uniform in colour than thulite usually is.
Among my other finds were two trace fossil argillite stones and a nice sized rhyolite with thin dark red bands. In the first trace fossil stone, the traces are darker in colour than the host rock while in the second they are lighter:
Finally, four other finds with interesting tiny details to them – and I am unable to identify what kind of stones they are, though the green in three of them is likely to come from the mineral epidote:
The next Post is on my second fossick at Gemstone Beach. An Index to this Series of Posts is available here.
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