Comparison · Silicate Minerals
Sillimanite vs Titanite
Sillimanite and Titanite are easy to confuse because both are silicate minerals. Sillimanite is harder (Mohs 7) than Titanite (Mohs 5.5), so Sillimanite will scratch Titanite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Sillimanite and Titanite
- Sillimanite is harder (Mohs 7) than Titanite (Mohs 5.5), so Sillimanite will scratch Titanite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
- They overlap in brown, green, and yellow, but Sillimanite also comes in white and gray and Titanite also comes in black.
- Well-formed crystals give it away: Sillimanite is orthorhombic, Titanite is monoclinic.
Sillimanite vs Titanite properties
| Property | Sillimanite | Titanite |
|---|---|---|
| Type | Silicate Minerals | Silicate Minerals |
| Mohs hardness | 7 | 5.5 |
| Luster | vitreous | adamantine |
| Streak | White | White |
| Transparency | transparent | transparent |
| Specific gravity | 3.24 | 3.5 |
| Crystal system | orthorhombic | monoclinic |
| Common colors | White, Gray, Brown, Pale green, Yellow | Green, Yellow, Brown, Black |
| Rarity | uncommon | uncommon |
| Typical specimen value | $10–$450+ | $15–$600+ |
Which is more valuable?
Titanite is usually the more valuable of the two: a typical collector specimen runs about $90 against $70 for Sillimanite, and premium Titanite can reach $600 or more.
About Sillimanite
Sillimanite is an aluminum silicate mineral that forms slender prismatic crystals or fibrous masses, the fibrous variety being called fibrolite. It is one of three aluminosilicate minerals that share the same composition but differ in structure.
About Titanite
Titanite, also called sphene, is a calcium titanium silicate known for its high luster, strong dispersion, and characteristic wedge-shaped crystals. Specimens are often green, yellow, or brown and may be transparent enough to facet, prized by collectors for their fire.
Sillimanite vs Titanite FAQ
Is Sillimanite the same as Titanite?
No. Both are silicate minerals, but they are distinct species with different hardness, streak or luster. Sillimanite is harder (Mohs 7) than Titanite (Mohs 5.5), so Sillimanite will scratch Titanite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
How can you tell Sillimanite from Titanite?
Sillimanite is harder (Mohs 7) than Titanite (Mohs 5.5), so Sillimanite will scratch Titanite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. They overlap in brown, green, and yellow, but Sillimanite also comes in white and gray and Titanite also comes in black. Well-formed crystals give it away: Sillimanite is orthorhombic, Titanite is monoclinic.
Which is harder, Sillimanite or Titanite?
Sillimanite is harder: Mohs 7 against Mohs 5.5 for Titanite.
Which is more valuable, Sillimanite or Titanite?
Titanite is usually the more valuable of the two: a typical collector specimen runs about $90 against $70 for Sillimanite, and premium Titanite can reach $600 or more.
