RocksdayBenitoite vs Tanzanite
How to tell them apart
A rare blue barium titanium silicate with distinctive triangular crystals.
Photo: Didier Descouens, CC BY-SA 4.0
Blue-violet zoisite found in only one small area of Tanzania. It shows different colors from different directions.
Photo: Didier Descouens, CC BY 3.0
Key differences
- Tanzanite crystals are prismatic, not triangular.
Side by side
| Property | Benitoite | Tanzanite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6–6.5 | 6–7 |
| Luster | Vitreous | Vitreous |
| Streak | White | White |
| Colors | Blue, White | Blue, Purple |
| Crystal system | Hexagonal | Orthorhombic |
| Specific gravity | 3.6–3.7 | 3.35 |
| Formula | BaTiSi₃O₉ | Ca₂Al₃(SiO₄)(Si₂O₇)O(OH) |
| Found in | San Benito County, California | Merelani Hills, Tanzania |
Properties that are the same for both are grayed out.
How to identify benitoite
- Sapphire-blue triangular crystals.
- Glows brilliant blue under shortwave UV light.
- Usually on white natrolite.
Crystal system: Hexagonal
Full Benitoite guide →How to identify tanzanite
- Blue to violet, shifting color as you rotate it.
- Hardness about 6.5 — softer than sapphire.
- Most rough is brownish until heated.
Crystal system: Orthorhombic
Full Tanzanite guide →More comparisons
Could you tell them apart from a blurry close-up?
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