Mohrite is a rare ammonium iron sulfate typically found as a secondary mineral in mine dumps or near volcanic fumaroles. It occurs as small, pale green prismatic crystals that are sensitive to dehydration and must be stored in closed containers to prevent weathering.
Is this mohrite?
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 mohrite with a known reference. Mohrite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mohrite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mohrite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: greenish-white, pale green, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, crusts.
Often confused with
Mohrite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mohrite
Minerals reported to co-occur with mohrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₂Fe(SO₄)₂·6H₂O
- Mohs hardness
- 2-3
- Density
- 2.12 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Crusts
- Cleavage
- Imperfect On {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumaroles, Mine Dumps
- Typical price
- $20-100 per specimen
Where rockhounds find mohrite
Classic worldwide localities
- Aue, Saxony, Germany
- Vesuvius, Italy
- Banská Štiavnica, Slovakia
Field-hunting tip
Look in fumaroles, mine dumps country — that is the host setting where mohrite typically forms. If you start seeing copiapite, jarosite, sulfur in float, you are in the right ground. Field specimens usually show a prismatic crystals, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find mohrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
