Comparison · Minerals
Gypsum vs Satin Spar
Gypsum and Satin Spar are easy to confuse because both are minerals. Both sit near Mohs 2, 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 Gypsum and Satin Spar
- Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Luster is different: Gypsum is vitreous, pearly, or silky (fibrous), earthy when massive while Satin Spar is silky.
- Hold a thin edge to the light: Gypsum is Transparent to translucent, Satin Spar is translucent.
- They overlap in clear and pink, but Gypsum also comes in gray, yellow, and brown.
- Well-formed crystals give it away: Gypsum is Monoclinic, Satin Spar is monoclinic.
Gypsum vs Satin Spar properties
| Property | Gypsum | Satin Spar |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 2 | 2 |
| Luster | Vitreous, pearly, or silky (fibrous), earthy when massive | silky |
| Streak | White | White |
| Transparency | Transparent to translucent | translucent |
| Specific gravity | 2.3–2.35 | 2.3 |
| Crystal system | Monoclinic | monoclinic |
| Common colors | Colorless, White, Gray, Yellow, Brown, Pink | White, Cream, Colorless, Peach |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $5–$120+ |
Which is more valuable?
Typical specimens of Gypsum and Satin Spar trade in a similar range, around $20.
About Gypsum
Gypsum is a soft, common evaporite mineral, calcium sulfate dihydrate with the formula CaSO4·2H2O, that defines hardness 2 on the Mohs scale and can be scratched with a fingernail. It precipitates from evaporating saline water and occurs in forms ranging from transparent selenite crystals to fibrous satin spar and massive alabaster. Gypsum is also the principal raw material used to manufacture plaster of Paris and drywall.
About Satin Spar
Satin Spar is a fibrous variety of gypsum recognized by its silky sheen, white to cream color, and soft hardness.
Gypsum vs Satin Spar FAQ
Is Gypsum the same as Satin Spar?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Gypsum from Satin Spar?
Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Luster is different: Gypsum is vitreous, pearly, or silky (fibrous), earthy when massive while Satin Spar is silky. Hold a thin edge to the light: Gypsum is Transparent to translucent, Satin Spar is translucent.
Which is harder, Gypsum or Satin Spar?
They are about equally hard, both near Mohs 2.
Which is more valuable, Gypsum or Satin Spar?
Typical specimens of Gypsum and Satin Spar trade in a similar range, around $20.
