"PM 2Ring" <nomail@nomail> schreef in bericht
news:web.445210571843be3376ba2c900@news.povray.org...
>
> Thanks, Thomas. It's always nice to get your geologist's approval of my
> stones.

Oh hum... <grin>

> Living in Sydney, I've seen weathered sandstone all my life, and plenty
> weathered by seepage. Sydney basin is built on sandstone and shale. As
well
> as the white, yellow and apricot colours of my palette, the real stones
have
> some beautiful shades of red, ranging from pale rose pinks to an almost
> purple colour. I know the reds & yellows come from iron, but I don't know
> about the purple.
>
It very much depends on the minerals in solution percolating through. Iron
of course, manganese like dlm says. I am not too familiar with that branch
of the trade. The irony is of course that I am living in a country that is
very poor in hard rock! But you can get the same kind of staining in sands
too, especially in the older deposits from the Pleistocene. And sands are
the building blocks of sandstones, so...


Thomas

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