Pearceite is a silver arsenic sulfosalt often found as distinct, triangular or hexagonal tabular crystals in silver-rich hydrothermal deposits. It is frequently associated with other silver minerals and is highly sought after by systematic mineral collectors for its sharp crystal morphology and metallic luster.
Is this pearceite?
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 pearceite with a known reference. Pearceite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive.
Often confused with
Pearceite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside pearceite
Minerals reported to co-occur with pearceite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- [Ag₉CuS₄][(Ag,Cu)₆(As,Sb)₂S₇]
- Mohs hardness
- 3
- Density
- 6.15 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque, translucent in very thin fragments
- Crystal system
- Monoclinic
- Crystal habit
- Granular, massive
- Cleavage
- Poor on {001}
- Rarity
- Uncommon
- Uses
- Collector, Ore mineral
- Host rock
- In hydrothermal deposits formed at low to medium temperatures
Where rockhounds find pearceite
Classic worldwide localities
- Drumlummon mine, Marysville, Lewis and Clark Co. (type locality), Montana, USA
- Neihart, Cascade Co., Montana, USA
- Molly Gibson mine, Aspen, Pitkin Co., and from Rico, Dolores Co., Colorado, USA
- Tintic district, Juab Co., at Eureka, Utah, USA
- Morrison mine, and in the Ross mine, Holtyre, Ontario, and at the Husky mine, Yukon Territory, Canada
- Veta Rica mine, Sierra Mojada, Coahuila, and as Reyes mine, Guanajuato, Mexico
Field-hunting tip
Where it forms: In hydrothermal deposits formed at low to medium temperatures. If you start seeing acanthite, silver, proustite in float, you are in the right ground. Typical habit: granular, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify pearceite?+
Where is pearceite found?+
Is pearceite safe to handle?+
What rocks look like pearceite?+
What minerals are found with pearceite?+
What kind of rock does pearceite form in?+
What is pearceite used for?+
Find pearceite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
