Where is Tanzanite found?

Tanzanite occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.

Where to find Tanzanite

Collecting tips

1. Geological Context. Tanzanite is found in highly specific geological settings, primarily in metamorphosed calcium-silicate rocks (skarns) within graphitic gneisses and schists. Prospecting requires a deep understanding of regional metamorphic geology.
2. Associated Minerals. Look for associated minerals such as graphite, diopside, grossular garnet, quartz, and various sulfide minerals. These can indicate the presence of the right geological environment.
3. Color and Pleochroism. Raw tanzanite often appears brownish-yellow or greenish-brown. The characteristic blue-violet color is usually developed after heat treatment. However, some naturally blue material exists. The strong pleochroism is a key identifying feature, even in rough material.
4. Crystal Habit. Tanzanite typically forms prismatic crystals, often with striations parallel to the c-axis. Look for these characteristic crystal forms within the host rock.

Quick Check

Color:

Blue to violet-blue (after heat treatment), brownish-yellow to greenish-brown (natural)

Luster:

Vitreous

Streak:

White

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