By Chisom Ibemere
Dravite is the basic form of tourmaline which is popular as the “Brown Tourmaline”. Crystals gotten from certain region are highly lustrous and beautifully crystallized. Dravite is named after Dravograd, in Slovenia, the area where it was first described. It is similar to Unvite and Fluor Uvite and may be very difficult to differentiate them. It is a member of the family, tourmaline. It is the least known stone of all the tourmaline varieties.
Dravite may occur in brown, dark orange-brown, dark yellow, brownish-black colours and rarely green, yellow, and orange. It has an Isometric crystal system. It has a hardness between 7 – 7.5, translucent to opaque with a specific gravity
of 3.0 – 3.2. It has a vitreous, resinous, dull lustre and cleavage of 3 and brittle.
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Dravite crystals can be short and stubby or elongated, and are basically terminated with a pointed triangular cross-section. It may also have multiple growth layers, and are commonly doubly terminated. They may occur as floater crystals.
Tourmaline occurs mainly in igneous rocks, particularly granite and granite pegmatite, and in metamorphic rocks like schist and marble. Schorl and lithium-rich tourmalines are basically seen in granite and granite pegmatite. Magnesium-rich tourmalines such as dravites, are restricted to schists and marble.
Dravite deposits may be seen in places like Abuja Atisbo, Oyo, in Nigeria. It has fetched more than $50,000 per carat and highly valued and prized across the globe.
