Tanzanite

Precious gem Birthstone of December Zoisite

6.5–7Hardness (Mohs)

Ca₂Al₃(SiO₄)₃(OH):VChemistry

1Known origins & mines

Found in one place on Earth: the Merelani Hills at the foot of Kilimanjaro. Discovered in 1967 when a lightning strike exposed violet-blue crystals; Tiffany & Co. named it after Tanzania. A December birthstone predicted to run out within a generation.

Known origins & mines

Merelani Block C · Tanzania

Active mining · Legendary locality

The industrial heart of tanzanite: deep shafts following zoisite veins in graphitic gneiss. Block D near-surface pockets yielded record 2200…