Anhydrite is an evaporite mineral that differs from gypsum by its lack of water in its chemical structure. It is easily recognized by its three directions of perfect cleavage at right angles, which often cause it to break into distinct cubic fragments.
Is this anhydrite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch anhydrite with a known reference. Anhydrite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Anhydrite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Anhydrite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, blue, violet, reddish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: tabular crystals, massive, granular, fibrous.
Often confused with
Anhydrite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside anhydrite
Minerals reported to co-occur with anhydrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSO₄
- Mohs hardness
- 3.5
- Density
- 2.9-3.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Tabular Crystals, Massive, Granular, Fibrous
- Cleavage
- Perfect in Three Directions At 90 Degrees
- Rarity
- Common
- Uses
- Industrial, Collector, Ornamental
- Host rock
- Sedimentary Evaporite Beds and Hydrothermal Veins
- Typical price
- $5-30 for thumbnail specimens, $50-200 for large display pieces
Where rockhounds find anhydrite
23 mapped spotsClassic worldwide localities
- Naica, Mexico
- Salzburg, Austria
- Haselgebirge, Germany
- New Jersey, USA
- Nova Scotia, Canada
U.S. states with anhydrite
Each link opens a state-specific list of mapped rockhounding spots that produce anhydrite.
Field-hunting tip
Look in sedimentary evaporite beds and hydrothermal veins country — that is the host setting where anhydrite typically forms. If you start seeing gypsum, halite, calcite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular, fibrous habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, Wyoming — start trip planning there.
Common questions
How do you identify anhydrite?+
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Find anhydrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
