Comparison · Minerals vs Borate Minerals
Satin Spar vs Ulexite
Satin Spar 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 Satin Spar and Ulexite
- Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Luster is different: Satin Spar is silky while Ulexite is vitreous.
- They overlap in clear, but Satin Spar also comes in pink.
- Well-formed crystals give it away: Satin Spar is monoclinic, Ulexite is triclinic.
Satin Spar vs Ulexite properties
| Property | Satin Spar | Ulexite |
|---|---|---|
| Type | Minerals | Borate Minerals |
| Mohs hardness | 2 | 2.5 |
| Luster | silky | vitreous |
| Streak | White | White |
| Transparency | translucent | translucent |
| Specific gravity | 2.3 | 1.95 |
| Crystal system | monoclinic | triclinic |
| Common colors | White, Cream, Colorless, Peach | White, Colorless |
| Rarity | common | uncommon |
| Typical specimen value | $5–$120+ | $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 Satin Spar, and premium Ulexite can reach $120 or more.
About Satin Spar
Satin Spar is a fibrous variety of gypsum recognized by its silky sheen, white to cream color, and soft hardness.
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.
Satin Spar vs Ulexite FAQ
Is Satin Spar the same as Ulexite?
No. Satin Spar 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 Satin Spar from Ulexite?
Both sit near Mohs 2, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Luster is different: Satin Spar is silky while Ulexite is vitreous. They overlap in clear, but Satin Spar also comes in pink.
Which is harder, Satin Spar or Ulexite?
Ulexite is harder: Mohs 2.5 against Mohs 2 for Satin Spar.
Which is more valuable, Satin Spar or Ulexite?
Ulexite is usually the more valuable of the two: a typical collector specimen runs about $25 against $20 for Satin Spar, and premium Ulexite can reach $120 or more.
