Comparison · Minerals vs Silicate Minerals
Andalusite vs Staurolite
Andalusite and Staurolite are easy to confuse. Both sit near Mohs 6.5–7.5, 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 Andalusite and Staurolite
- Both sit near Mohs 6.5–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Andalusite leaves a white streak on unglazed porcelain, Staurolite leaves white to grayish.
- Staurolite feels noticeably heavier for its size (specific gravity 3.7 versus 3.13–3.21 for Andalusite).
- Hold a thin edge to the light: Andalusite is Transparent to translucent, Staurolite is translucent.
- They overlap in brown and red, but Andalusite also comes in green, gray, and pink and Staurolite also comes in black.
- Well-formed crystals give it away: Andalusite is Orthorhombic, Staurolite is monoclinic.
Andalusite vs Staurolite properties
| Property | Andalusite | Staurolite |
|---|---|---|
| Type | Minerals | Silicate Minerals |
| Mohs hardness | 6.5–7.5 | 7.25 |
| Luster | Vitreous | vitreous |
| Streak | White | White to grayish |
| Transparency | Transparent to translucent | translucent |
| Specific gravity | 3.13–3.21 | 3.7 |
| Crystal system | Orthorhombic | monoclinic |
| Common colors | Reddish brown, Olive green, Gray, Pink | Reddish brown, Brown, Dark brown, Black |
| Rarity | common | uncommon |
| Typical specimen value | $2–$150+ | $5–$300+ |
Which is more valuable?
Staurolite is usually the more valuable of the two: a typical collector specimen runs about $45 against $20 for Andalusite, and premium Staurolite can reach $300 or more.
About Andalusite
Andalusite is an aluminum silicate, Al2SiO5, and one of three natural polymorphs sharing that exact formula along with kyanite and sillimanite. It crystallizes in the orthorhombic system as stout, nearly square prisms formed under low-pressure, moderate-temperature metamorphism. Its variety chiastolite, which displays a dark cross pattern in cross-section, makes it one of the more recognizable metamorphic minerals to casual collectors.
About Staurolite
Staurolite is an iron aluminum silicate famous for its cross-shaped twinned crystals. It forms reddish-brown to nearly black prismatic crystals in metamorphic schists and is a classic index mineral of medium-grade metamorphism.
Andalusite vs Staurolite FAQ
Is Andalusite the same as Staurolite?
No. Andalusite is a mineral while Staurolite is a silicate mineral. Both sit near Mohs 6.5–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Andalusite from Staurolite?
Both sit near Mohs 6.5–7.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Andalusite leaves a white streak on unglazed porcelain, Staurolite leaves white to grayish. Staurolite feels noticeably heavier for its size (specific gravity 3.7 versus 3.13–3.21 for Andalusite).
Which is harder, Andalusite or Staurolite?
They are about equally hard, both near Mohs 6.5–7.5.
Which is more valuable, Andalusite or Staurolite?
Staurolite is usually the more valuable of the two: a typical collector specimen runs about $45 against $20 for Andalusite, and premium Staurolite can reach $300 or more.
