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, 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.
