Chrysocolla
(c) 2001 Andrew Alden, licensed to About.com, Inc. (fair use policy)
Where you see bright blue-green chrysocolla, you'll know that copper is nearby. Chrysocolla is a hydroxylated copper silicate mineral that forms in the alteration zone around the edges of copper ore bodies. It almost always occurs in the amorphous, noncrystalline form shown here.
This specimen has an abundance of chrysocolla coating the grains of a breccia. The picture doesn't really do justice to the color, which is close to turquoise. Real turquoise is much harder (Mohs hardness 6) than chrysocolla (hardness 2 to 4), but sometimes the softer mineral is passed off as turquoise.
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