Mutnovskite is a rare lead arsenic sulfotelluride mineral discovered in the fumaroles of the Mutnovsky volcano. It is typically found as small, metallic-looking grains or intergrowths within volcanic sublimates, making it a highly prized specimen for advanced mineral collectors.
Is this mutnovskite?
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 mutnovskite with a known reference. Mutnovskite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine.
- 4Match the color rangeCompare against the expected color range: ruby red, brownish red.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: blocky, microscopic crystals, prismatic.
Often confused with
Mutnovskite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Mutnovskite leaves gray, Galena leaves lead-gray; luster reads subadamantine on Mutnovskite and metallic on Galena.
How to tell apart: Streak differs, so Mutnovskite leaves gray, Tetradymite leaves pale steel-gray; luster reads subadamantine on Mutnovskite and metallic, splendent on fresh surfaces on Tetradymite.
Often found alongside mutnovskite
Minerals reported to co-occur with mutnovskite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₂AsS₃(I,Cl,Br)
- Mohs hardness
- 2
- Density
- 6.6-6.7 g/cm³
- Colors
- Ruby redBrownish red
- Streak
- Gray
- Luster
- Subadamantine
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Blocky, microscopic crystals, prismatic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic sublimates (250 deg C) in fumaroles
Where rockhounds find mutnovskite
Classic worldwide localities
- Mutnovsky volcano, Kamchatka Peninsula, Russia (type locality)
Field-hunting tip
Where it forms: Volcanic sublimates (250 deg C) in fumaroles. If you start seeing galena, gold, tellurium in float, you are in the right ground. Typical habit: blocky, microscopic crystals, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find mutnovskite on the map
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