Feature Gems & Gemology, Summer 1999, Volume 35, No. 2

Sapphire and Garnet from Kalalani, Tanga Province, Tanzania

Located just 3 km south of the famous Umba locality, the geologically similar Kalalani area hosts deposits of gem-quality sapphire (reddish orange, yellow-brown, and other colors), pyrope-almandine, and tsavorite. The gems are mined principally from primary and eluvial sources associated with a serpentinite body and surrounding metacalcareous rocks. The gemological properties of sapphires from Kalalani are very similar or identical to those from Umba. The garnets, however, are different: Tsavorite is not known from the Umba area, and the dark red to brownish red pyrope-almandine from Kalalani is distinct from the pink-purple rhodolite more commonly found at Umba.