Pearceite
A variety of Minerals
What is Pearceite?
Pearceite is one of the four so-called "ruby silvers", pearceite Cu(Ag,Cu)6Ag9As2S11, pyrargyrite Ag3SbS3, proustite Ag3AsS3 and miargyrite AgSbS2. It was discovered in 1896 and named after Dr Richard Pearce (1837–1927), a Cornish–American chemist and metallurgist from Denver, Colorado.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Pearceite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Pearceite Localities Map
See where Pearceite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Pearceite
Pearceite is often granular and massive; crystals are short, tabular pseudohexagonal prisms with bevelled edges, showing triangular striations on faces parallel to the plane containing the a and b axes, and rosettes of such crystals, to 3 cm across. The mineral is black, and in polished section it is white with very dark red internal reflections. It has a black to reddish black streak and a metallic luster, generally opaque, but translucent in very thin fragments. It is biaxial with a very high refractive index of 2.7 and maximum birefringence δ also 2.7. Dispersion of the optic axes is relatively strong. Reflected light anisotropism is the property of appearing to change color when viewed under crossed polarised light in a reflected light microscope. Pearceite exhibits moderate anisotropism, often dark violet. The color in reflected plane polarised light is white, with very dark red internal reflections and very weak pleochroism in air, fair in oil. Reflectivity in air at 540 nm is about 30%. It is not fluorescent. Pearceite is a brittle mineral that breaks with a conchoidal to irregular fracture. It is soft, with hardness only 3, the same as calcite. The silver content gives it a high specific gravity of 6.15, the highest of the ruby silvers. Cleavage is either absent or poor. The mineral is neither magnetic nor radioactive.
Quick Facts
Physical Properties
- Color
- black with dark red internal reflections
- Hardness (Mohs)
- 2.5 - 3
- Streak
- black
Chemical Properties
- Chemical Formula
- [Ag9CuS4][(Ag,Cu)<sub>6</sub>(As,Sb)<sub>2</sub>S<sub>7</sub>]
- Elements
- Ag, As, Cu, S, Sb
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Pearceite FAQs
How do I identify Pearceite?
Pearceite can be identified by its hardness of 2.5 - 3 on the Mohs scale, black with dark red internal reflections color. Look for these key characteristics when examining specimens.
What color is Pearceite?
Pearceite typically appears in black with dark red internal reflections. Color can vary depending on impurities and formation conditions.
How hard is Pearceite?
Pearceite has a hardness of 2.5 - 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the characteristics of pearceite of Pearceite?
Pearceite is often granular and massive; crystals are short, tabular pseudohexagonal prisms with bevelled edges, showing triangular striations on faces parallel to the plane containing the a and b axes, and rosettes of such crystals, to 3 cm across. The mineral is black, and in polished section it is white with very dark red internal reflections. It has a black to reddish black streak and a metallic luster, generally opaque, but translucent in very thin fragments. It is biaxial with a very high refractive index of 2.7 and maximum birefringence δ also 2.7. Dispersion of the optic axes is relatively strong. Reflected light anisotropism is the property of appearing to change color when viewed under crossed polarised light in a reflected light microscope. Pearceite exhibits moderate anisotropism, often dark violet. The color in reflected plane polarised light is white, with very dark red internal reflections and very weak pleochroism in air, fair in oil. Reflectivity in air at 540 nm is about 30%. It is not fluorescent. Pearceite is a brittle mineral that breaks with a conchoidal to irregular fracture. It is soft, with hardness only 3, the same as calcite. The silver content gives it a high specific gravity of 6.15, the highest of the ruby silvers. Cleavage is either absent or poor. The mineral is neither magnetic nor radioactive.
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