On Tuesday I drove from the south coast of Southland to Kakanui in North Otago. I stopped off at Dunedin to meet Nick Mortimer, the geologist who provided comments on the final draft of “What’s This Stone? A Photographic Collection of Finds from Gemstone Beach”. I stayed that night at a crib/bach/holiday home in Kakanui village that I booked through Booking.com.
It was 7am on Wednesday morning when I arrived at Kakanui’s Seadown Beach, just a few minutes after low tide. My aim was to get access to the rocks at the south end of the beach while the tide was out. It was only five degrees with a light wind blowing though the sun was out, sitting low in the sky. On the way there, I had noticed at least a dozen cars parked at the bridge over the Kakanui River, whitebaiters who had risen even earlier than myself. I found that at least a metre of sand had been moved from the rocks at the south end of Seadown Beach, making access easier than usual, though I did not find much of interest among the scattered stones there during my 90 minutes on the beach. I did come across a couple of large quartzite rocks, one of which appears in the photos below. The close-up image shows what is sometimes called fingernail marks on its surface.
This was probably one of my most unproductive fossicks here. However, here are eight stones I collected this morning. Two of them are what is called limonite prase, a type of brown jasper often with black markings:
One of the gorgeous yellow/orange quartzites common on this beach:
I thought this stone might also be a quartzite but it has unusual white flecks in it – it’s probably a variation:
Interesting dark red jaspers can also be found here – see the entry for Saturday 22 May 2021 in this Post. This morning I found this small brecciated one with quartz veins:
I picked up this lemon coloured quartz:
This dark stone with circular (sphericular) features is one I’ve seen two or three times before and I know it occurs further north, near Timaru, as well:
Finally, even though it is not a stone for tumble polishing. I sometimes pick up a specimen of Kakanui Mineral Breccia, like this one – which contains green and dark red crystals, the former probably chrome diopside and the latter probably garnet:
Kakanui Mineral Breccia is a rare, mineral-rich fragmental volcanic rock formed approximately 34 million years ago when ascending magma interacted violently with water in an underwater volcanic vent. It has attracted international geological attention. For more information, see this Post.
After my time at Seadown Beach, I drove a couple of kilometres north to Beach Road Reserve for a brief fossick. An Index to all the Posts in this Series is here.
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