Minerals from Tanzania

Tanzania is one of Africa’s most important sources of gemstones and mineral specimens, with a range of pegmatites and metamorphic deposits across the country.

The Merelani Hills are the most famous locality, best known for producing Tanzanite – a blue to violet variety of zoisite. While most of the material is cut for the gemstone market, crystal specimens do exist and can be quite striking. Merelani also yields fine clinozoisite, diopside, graphite, and exceptional green grossular garnet (tsavorite), along with occasional axinite and prehnite.

The Umba Valley is another significant gemstone area, producing a wide variety of alluvial gemstones including sapphire, spinel, zircon, garnet, and tourmaline. Most are found as rolled pebbles, though rough crystals are sometimes collected for specimen use.

Tanzania’s pegmatites have produced good quality aquamarine, tourmaline, and occasionally rare minerals such as pollucite and columbite. These are usually associated with the central and southern parts of the country, though they are not as well-documented or frequently seen as Merelani material.

Ruby is mined in the Winza and Longido areas. While many of the crystals are fractured or opaque, there are some excellent red corundum specimens in matrix or as waterworn crystals. Some of the Longido material is found in green zoisite matrix and is sometimes mislabelled as Tanzanite.

Tanzania continues to be a very active source country, and a steady stream of new discoveries and mineral types appear on the market, especially via dealers based in Arusha and Nairobi.

Tanzania