Catalog Search Guide
You can search our catalog using different mineral attributes. For example, you can search by color such as green, yellow or purple, or by chemical elements such as uranium, calcium or iron, or by mineral groups such as phosphate, silicate or carbonate. You can also filter by crystal habit like crystal, geode or crystal on matrix, by specimen size such as thumbnail, small, medium or cabinet, and by features such as radioactive or fluorescent minerals.
Tanzania
Tanzania is East Africa's premier gem-mineral country, built on the ancient Tanzania Craton and ringed by the metamorphic Mozambique Belt, whose Pan-African graphitic marbles and gneisses host the world's most concentrated gem-pegmatite and hydrothermal deposits. No locality on Earth is more celebrated than Merelani Hills near Arusha, the sole commercial source of tanzanite, the blue-violet variety of zoisite colored by trace vanadium, and also a producer of fine green grossular garnet (tsavorite), diopside, prehnite, and magnesio-axinite on the same graphitic-marble matrix. Nearby occurrences in the Simanjiro District, including Landanai, yield vivid chromium-bearing dravite, marketed as chrome tourmaline, associated with calcite, pyrite, and rutile in marble.
Southern Tanzania is equally storied for collectors: the Mahenge district in Morogoro Region is world-famous for gem-quality red-pink spinel crystals and octahedra, alongside garnet and tourmaline, while the Umba Valley in the north produces a striking rainbow of corundum (ruby and sapphire) and multicolored garnets—almandine, pyrope, spessartite, and color-change grossular—colored by iron, chromium, manganese, and vanadium. Tunduru and Songea in Ruvuma Region, and Winza in Dodoma, add further alluvial sapphire, ruby, and garnet finds, while Sangolungulu is a classic source of lustrous spessartite garnet on mica. Morogoro itself has also produced fine gemmy danburite crystals, a scarcer species prized by systematic collectors.
What makes Tanzanian material so desirable is this rare combination of monomineralic rarity—tanzanite exists commercially nowhere else—with genuine mineralogical diversity spanning silicates, garnets, spinels, and borosilicates, all tied to a single dynamic Precambrian-to-Pan-African geological history. Merelani specimens showing tanzanite intergrown with diopside or prehnite, Mahenge spinel on matrix, and Umba parti-color garnets are especially sought by museums and connoisseurs, since Tanzania's artisanal mining methods often preserve natural crystal faces and matrix relationships lost in more mechanized mining regions. For collectors seeking East African provenance, aesthetic crystal habit, and true species rarity, Tanzania remains an essential country of origin.
