I picked up this rock on the beach at Koh Libong, an island on the South of Thailand, the region has lots of Karst type formations but the rocks there looked different, dark red mostly and with lots of banding and inclusions (correct me if I am wrong in the terminology, I’m just a step above zero level in geology)
Anyway, some pictures, I rinsed it to make the colours and details stand out more, the grid is 1cm squares:
I don’t recall ever seeing something like this (although there were many similar rocks on the beach), I guess it’s some type of limestone stained by iron for the red, but that’s all I could venture.
It looks a bit like it could have been altered by the heat of a beach fire - is that a possibilitiy? You say there were others like it on the beach - were the rocks like this clustered at all?
No, just scattered all along the beach, although most of them were dark red to purplish, same as the larger rock formations, and on those I didn’t see any patterns like on this one; there was however an outcrop with thin (2 to 5mm) veins of a crystalline white material, quartz maybe.
I’m not convinced those rocks in China really look like that in real life. I’m wondering about filtering being used etc. Here’s a youtube vid. They’re still pretty and they are colourful and maybe on a really bright sunny day they would take on even more colour but they don’t look like a Van Gogh painting
The colors look spot on, but I don’t know if mine could be polished as I see in the image search; it would look really nice though!.
From this wiki entry (Radiolarite) it seems to be sedimentary and marine in origin, but as I said the texture on my rock is more like sandstone/limestone than what I see in the pictures, but then again I found it on the shore so it’s been roughed up by the sand.
Any suggestions on polishing without a rock tumbler?
I’m not convinced those rocks in China really look like that in real life. I’m wondering about filtering being used etc. Here’s a youtube vid. They’re still pretty and they are colourful and maybe on a really bright sunny day they would take on even more colour but they don’t look like a Van Gogh painting
[/QUOTE]
I’m sure the more vivid photos had their colour saturation cranked up to eleven. Still looks gorgeous in the more subdued ones too.
After 20 minutes sanding a patch down with 240 grit wet sandpaper, I’m not sure it will take a polish, but it’s smoother now.
Surprisingly the darker parts seem to sand easier, or at least the sludge from wet sanding picks up a vivid mauve colour very quickly.
