Comparison · Minerals vs Borate Minerals
Gypsum vs Ulexite
Gypsum and Ulexite are easy to confuse. 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 Ulexite
- Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Hold a thin edge to the light: Gypsum is Transparent to translucent, Ulexite is translucent.
- They overlap in clear, but Gypsum also comes in gray, yellow, brown, and pink.
- Well-formed crystals give it away: Gypsum is Monoclinic, Ulexite is triclinic.
Gypsum vs Ulexite properties
| Property | Gypsum | Ulexite |
|---|---|---|
| Type | Minerals | Borate Minerals |
| Mohs hardness | 2 | 2.5 |
| Luster | Vitreous, pearly, or silky (fibrous), earthy when massive | vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | translucent |
| Specific gravity | 2.3–2.35 | 1.95 |
| Crystal system | Monoclinic | triclinic |
| Common colors | Colorless, White, Gray, Yellow, Brown, Pink | White, Colorless |
| Rarity | common | uncommon |
| Typical specimen value | $2–$150+ | $5–$120+ |
Which is more valuable?
Ulexite is usually the more valuable of the two: a typical collector specimen runs about $25 against $20 for Gypsum, and premium Ulexite can reach $120 or more.
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 Ulexite
Ulexite is a hydrated sodium calcium borate best known for its fibrous variety, which transmits light along its fibers. Sliced and polished plates project an image from the back surface, earning it the nickname television stone.
Gypsum vs Ulexite FAQ
Is Gypsum the same as Ulexite?
No. Gypsum is a mineral while Ulexite is a borate mineral. 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 Ulexite?
Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Hold a thin edge to the light: Gypsum is Transparent to translucent, Ulexite is translucent. They overlap in clear, but Gypsum also comes in gray, yellow, brown, and pink.
Which is harder, Gypsum or Ulexite?
Ulexite is harder: Mohs 2.5 against Mohs 2 for Gypsum.
Which is more valuable, Gypsum or Ulexite?
Ulexite is usually the more valuable of the two: a typical collector specimen runs about $25 against $20 for Gypsum, and premium Ulexite can reach $120 or more.
