Jos, Kaduna, Nigeria

Sapphire-bearing placer deposit near Jos in the southeastern part of Kaduna state.

Sapphires in association with hematite, goethite, and gibbsite are extracted from the upper horizon of alluvial deposits, 0.5 to 1 m from the surface. Sapphire crystals have barrel-like, tabular or prismatic shapes and are partly rounded. The colour is mostly blue and less often yellow. Refractive index is 1.759 - 1.771. Solid inclusions in sapphires include zircon, albite and uranpyrochlore.

Because of their dark colour, the blue sapphires from Kaduna are mainly cut into cabochons.

Ref: E.Ya. Kievlenko (2003) Geology of gems, p. 68

Gemstone List

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