Malachite, a copper oxide based mineral has been mined in several parts of the world. When I was small, one of my uncles worked for some years in East Africa where malachite was (is?) often used as a decorative feature on jewellery. This is a part view of a brooch belonging to my mum.
My train set was based on a Zambian copper mine. It is possible to extract the copper from malachite, although the use of sulphuric acid brings, as you might expect, a variety of environmental concerns.
Thanks to Freespiral for hosting Tiny Tuesday.