Comparison · Semi-Precious Stones vs Silicate Minerals
Tanzanite vs Zoisite
Tanzanite and Zoisite are easy to confuse. Both sit near Mohs 6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Tanzanite and Zoisite
- Both sit near Mohs 6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- They overlap in blue, but Tanzanite also comes in purple and Zoisite also comes in green, pink, and gray.
Tanzanite vs Zoisite properties
| Property | Tanzanite | Zoisite |
|---|---|---|
| Type | Semi-Precious Stones | Silicate Minerals |
| Mohs hardness | 6.5 | 6.5 |
| Luster | vitreous | vitreous |
| Streak | White | White |
| Transparency | transparent | transparent |
| Specific gravity | 3.35 | 3.3 |
| Crystal system | orthorhombic | orthorhombic |
| Common colors | Blue, Violet, Purple | Green, Pink, Blue, Gray |
| Rarity | legendary | uncommon |
| Typical specimen value | $300–$10000+ | $12–$450+ |
Which is more valuable?
Tanzanite is usually the more valuable of the two: a typical collector specimen runs about $1000 against $70 for Zoisite, and premium Tanzanite can reach $10000 or more.
About 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.
About Zoisite
Zoisite is a calcium aluminum silicate that occurs in striated prismatic crystals and massive aggregates. Best known through its blue-violet gem variety tanzanite and the pink variety thulite, it is both a metamorphic mineral and a notable gemstone.
Tanzanite vs Zoisite FAQ
Is Tanzanite the same as Zoisite?
No. Tanzanite is a semi-precious stone while Zoisite is a silicate mineral. Both sit near Mohs 6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Tanzanite from Zoisite?
Both sit near Mohs 6.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. They overlap in blue, but Tanzanite also comes in purple and Zoisite also comes in green, pink, and gray.
Which is harder, Tanzanite or Zoisite?
They are about equally hard, both near Mohs 6.5.
Which is more valuable, Tanzanite or Zoisite?
Tanzanite is usually the more valuable of the two: a typical collector specimen runs about $1000 against $70 for Zoisite, and premium Tanzanite can reach $10000 or more.
