Mascagnite is an ammonium sulfate mineral typically found as a sublimated crust around volcanic fumaroles or in areas of burning coal seams. It is highly water-soluble, meaning specimens must be kept in sealed containers in a dry, cool environment to prevent deliquescence or dissolution.
Is this mascagnite?
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 mascagnite with a known reference. Mascagnite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mascagnite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mascagnite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, yellow, gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crusts, stalactitic, efflorescences.
Often confused with
Mascagnite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside mascagnite
Minerals reported to co-occur with mascagnite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (NH₄)₂SO₄
- Mohs hardness
- 2.5
- Density
- 1.77 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Crusts, Stalactitic, Efflorescences
- Cleavage
- Distinct On {010}
- Rarity
- Uncommon
- Uses
- Collector, Scientific
- Host rock
- Volcanic Fumaroles, Coal Mine Fires
- Typical price
- $20-100 for small samples
Where rockhounds find mascagnite
Classic worldwide localities
- Vesuvius, Italy
- Etna, Italy
- Lipari Islands, Italy
- Cerro de Pasco, Peru
Field-hunting tip
Look in volcanic fumaroles, coal mine fires country — that is the host setting where mascagnite typically forms. If you start seeing sulfur, sal ammoniac, gypsum in float, you are in the right ground. Field specimens usually show a crusts, stalactitic, efflorescences habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find mascagnite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
