Laphamite is a rare arsenic selenide mineral primarily found as a sublimation product in burning coal mine dumps. It is easily identified by its distinctive red platy crystals or coatings which are formed by the condensation of gases near active vents.
Is this laphamite?
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 laphamite with a known reference. Laphamite sits at Mohs 1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish orange.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: dark red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic.
Often confused with
Laphamite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside laphamite
Minerals reported to co-occur with laphamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- As₂Se₃
- Mohs hardness
- 1-2
- Density
- 4.5 g/cm³
- Colors
- Streak
- Reddish orange
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As a secondary incrustation, probably by sublimation, on clinker adjacent to a surface vent on a burning pile of waste material from an anthracite coal mine
Where rockhounds find laphamite
Classic worldwide localities
- Burnside, Northumberland Co., Pennsylvania, USA (type locality)
Field-hunting tip
Where it forms: As a secondary incrustation, probably by sublimation, on clinker adjacent to a surface vent on a burning pile of waste material from an anthracite coal mine. If you start seeing arsenolite, orpiment in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify laphamite?+
Where is laphamite found?+
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What rocks look like laphamite?+
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Find laphamite on the map
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