| Gewicht | 3,31 kg (3,310 gr) |
|---|---|
| Dimensions | 20 × 14 × 8 cm |
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| Type | |
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| Origin | |
| SKU | 22072 |
Zwarte Toermalijn Ruw
Sales unit: Unique
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Black Tourmaline Rough from India
Tourmaline
Tourmaline is a group of borosilicate minerals with a complex chemical composition and a wide variety of colours. It occurs in virtually every colour of the rainbow, including pink, green, blue, black and multi-coloured combinations. This variety makes tourmaline one of the most popular gemstones in the jewellery world.
Tourmaline usually forms in pegmatites and metamorphic rocks. Major deposits include Brazil, Afghanistan, Mozambique, Nigeria and the United States. The chemical formula varies, but a general form is (Ca,K,Na)(Al,Fe,Li,Mg,Mn)₃(Al,Cr,Fe,V)₆(BO₃)₃(Si,Al,B)₆O₁₈(OH,F)₄. The hardness is between 7 and 7.5 on the Mohs scale.
Popular varieties include black tourmaline (schörl), pink tourmaline (rubellite), green tourmaline (verdelite) and watermelon tourmaline (pink interior, green rim).
Sources:
Mindat.org, Gemdat.org, Wikipedia - Tourmaline
