Comparison · Minerals
Anhydrite vs Cavansite
Anhydrite and Cavansite are easy to confuse because both are minerals. Both sit near Mohs 3–3.5, 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 Anhydrite and Cavansite
- Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Anhydrite leaves a white streak on unglazed porcelain, Cavansite leaves pale blue.
- Anhydrite feels noticeably heavier for its size (specific gravity 2.9–3.0 versus 2.21–2.31 for Cavansite).
- They overlap in blue, but Anhydrite also comes in clear, gray, and pink.
Anhydrite vs Cavansite properties
| Property | Anhydrite | Cavansite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3–3.5 | 3–4 |
| Luster | Vitreous, pearly on cleavage surfaces | Vitreous |
| Streak | White | Pale blue |
| Transparency | Transparent to translucent | Transparent to translucent |
| Specific gravity | 2.9–3.0 | 2.21–2.31 |
| Crystal system | Orthorhombic | Orthorhombic |
| Common colors | Colorless, White, Gray, Blue, Pink | Bright blue, Deep blue |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Anhydrite and Cavansite trade in a similar range, around $20.
About Anhydrite
Anhydrite is calcium sulfate, CaSO4, chemically identical to gypsum but lacking the water molecules bound into gypsum's crystal structure. It forms in evaporite basins where seawater or saline lake water concentrates through evaporation, and it readily absorbs water to convert into gypsum, which is why anhydrite outcrops are less common at the surface than at depth. Its name, from the Greek for "without water," directly references this dehydrated composition.
About Cavansite
Cavansite is a rare hydrous calcium vanadium silicate, Ca(VO)Si4O10 4H2O, notable for an intense, almost electric blue color rarely matched by other minerals. It crystallizes in the orthorhombic system, typically as radiating clusters of thin blades lining cavities in basalt. First described in 1967, it remains one of the few common minerals containing vanadium as an essential structural element.
Anhydrite vs Cavansite FAQ
Is Anhydrite the same as Cavansite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Anhydrite from Cavansite?
Both sit near Mohs 3–3.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Anhydrite leaves a white streak on unglazed porcelain, Cavansite leaves pale blue. Anhydrite feels noticeably heavier for its size (specific gravity 2.9–3.0 versus 2.21–2.31 for Cavansite).
Which is harder, Anhydrite or Cavansite?
They are about equally hard, both near Mohs 3–3.5.
Which is more valuable, Anhydrite or Cavansite?
Typical specimens of Anhydrite and Cavansite trade in a similar range, around $20.
