Black tourmaline, crystal group

Three black prismatic crystals, triangular in section and striated over their whole length, joined in a natural group.

The minerals of southern Morocco come from the old copper deposits of the Anti-Atlas and the hills around Ouarzazate. Azurite and malachite, both copper carbonates, are born from the weathering of these veins: which is why they are almost always found together, the blue slowly turning green on contact with damp.

Raw specimen, neither cut nor treated. The dimensions are estimated from the coin used for scale in the original photograph.