Semi-Precious Stones · legendary
Tanzanite
Tanzanite is a blue-violet variety of zoisite found only in Tanzania. It's 1,000 times rarer than diamond and was only discovered in 1967.
Also known as: december birthstone, blue zoisite, african gem.
Tanzanite properties at a glance
| Type | Semi-Precious Stones |
|---|---|
| Chemical formula | Ca2Al3(SiO4)3(OH) |
| Mohs hardness | 6.5 |
| Crystal system | orthorhombic |
| Luster | vitreous |
| Streak | White |
| Cleavage | Perfect |
| Fracture | Uneven |
| Specific gravity | 3.35 |
| Transparency | transparent |
| Common colors | Blue, Violet, Purple |
| Rarity | legendary |
Geology & background
Forms through regional metamorphism of vanadium-bearing rocks in the presence of hydrothermal fluids.
Discovered in 1967 and popularized by Tiffany & Co., making it one of the most recent gemstone discoveries.
How to identify Tanzanite
- Check whether the specimen's color and texture match typical Tanzanite examples.
- Photograph a fresh surface in natural light and avoid shadows, glare, or wet surfaces.
- Use hardness, streak, luster, grain size, and locality together; no single trait is enough for every specimen.
Full Tanzanite identification guide: checklist, home tests and look-alikes →
Tanzanite vs similar stones
Not sure it isn't something else? Side-by-side comparisons with the stones most often confused with Tanzanite.
Where Tanzanite is found
Tanzanite is reported from multiple localities or geological settings. Exact locality should be verified from specimen provenance, maps, or field notes.
How much is Tanzanite worth?
| Entry-level specimen | $300 |
|---|---|
| Typical collector specimen | $1000 |
| Premium specimen | $10000+ |
Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
Common uses
- Jewelry
- Collector specimens
Interesting facts
- Found in only one location on Earth
- Named by Tiffany & Co. after Tanzania
- May be depleted within 20-30 years
Care & safety
Treat Tanzanite as a collector specimen unless hardness, cleavage, and fracture are confirmed.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.
Tanzanite FAQ
What is Tanzanite?
Tanzanite is a blue-violet variety of zoisite found only in Tanzania. It's 1,000 times rarer than diamond and was only discovered in 1967.
How much is Tanzanite worth?
Entry-level Tanzanite specimens sell for around $300, a typical collector specimen for about $1000, and premium pieces for $10000 or more. Value depends on size, condition, color, crystal quality, locality, rarity, preparation, and provenance. Treat this as educational guidance, not an appraisal.
How hard is Tanzanite?
Tanzanite has a Mohs hardness of 6.5. It scratches glass and a steel knife and cannot be scratched by a steel file.
Where is Tanzanite found?
Notable sources of Tanzanite include Tanzania (only source). Forms through regional metamorphism of vanadium-bearing rocks in the presence of hydrothermal fluids..
What is Tanzanite used for?
Tanzanite is used for jewelry and collector specimens.
