Comparison · Minerals
Anhydrite vs Halite
Anhydrite and Halite are easy to confuse because both are minerals. Anhydrite is harder (Mohs 3–3.5) than Halite (Mohs 2–2.5), so Anhydrite will scratch Halite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Anhydrite and Halite
- Anhydrite is harder (Mohs 3–3.5) than Halite (Mohs 2–2.5), so Anhydrite will scratch Halite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
- Anhydrite feels noticeably heavier for its size (specific gravity 2.9–3.0 versus 2.1–2.2 for Halite).
- Well-formed crystals give it away: Anhydrite is Orthorhombic, Halite is Isometric.
Anhydrite vs Halite properties
| Property | Anhydrite | Halite |
|---|---|---|
| Type | Minerals | Minerals |
| Mohs hardness | 3–3.5 | 2–2.5 |
| Luster | Vitreous, pearly on cleavage surfaces | Vitreous |
| Streak | White | White |
| Transparency | Transparent to translucent | Transparent to translucent |
| Specific gravity | 2.9–3.0 | 2.1–2.2 |
| Crystal system | Orthorhombic | Isometric |
| Common colors | Colorless, White, Gray, Blue, Pink | Colorless, White, Pink, Blue, Gray |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $2–$150+ |
Which is more valuable?
Typical specimens of Anhydrite and Halite 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 Halite
Halite is naturally occurring sodium chloride, NaCl, the mineral form of common table salt, and one of the few minerals people regularly taste-test in the field. It crystallizes in the isometric system with perfect cubic cleavage in three directions at right angles, producing sharp, blocky crystals. Halite forms through the evaporation of saline water, making it a defining evaporite mineral.
Anhydrite vs Halite FAQ
Is Anhydrite the same as Halite?
No. Both are minerals, but they are distinct species with different hardness, streak or luster. Anhydrite is harder (Mohs 3–3.5) than Halite (Mohs 2–2.5), so Anhydrite will scratch Halite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
How can you tell Anhydrite from Halite?
Anhydrite is harder (Mohs 3–3.5) than Halite (Mohs 2–2.5), so Anhydrite will scratch Halite and not the other way round. A fingernail (Mohs 2.5) scratches it easily. Anhydrite feels noticeably heavier for its size (specific gravity 2.9–3.0 versus 2.1–2.2 for Halite). Well-formed crystals give it away: Anhydrite is Orthorhombic, Halite is Isometric.
Which is harder, Anhydrite or Halite?
Anhydrite is harder: Mohs 3–3.5 against Mohs 2–2.5 for Halite.
Which is more valuable, Anhydrite or Halite?
Typical specimens of Anhydrite and Halite trade in a similar range, around $20.
