Ruby and sapphire deposits of the anorthosite type are known in the Umba River Valley and in the region of Longido in northern Tanzania, near the Kenyan border. They are bodies of metamorphosed ultramafic rocks, which are part of the older Precambrian Usagaran group of granite gneisses, crystalline schists, quartzites, and dolomites within the Mozambique foldbelt.

Ref: E.Ya. Kievlenko, Geology of gems, 2003, p. 59

Gemstone List

Gem list contains entries from all listed localities in region.

Gemstones from Tanzania by Colour

Click on a photo for more information.

Localities in this Region

Copyright © Jolyon & Katya Ralph 1993-2020. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.