Cuboargyrite is a rare high-temperature polymorph of silver sulfide that typically occurs as cubic crystals. It is chemically identical to acanthite but crystallizes in the isometric system, often appearing as an inversion product. Collectors usually find it as small, metallic-gray crystals within complex silver-bearing hydrothermal vein systems.
Is this cuboargyrite?
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 cuboargyrite with a known reference. Cuboargyrite 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: grayish black.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains.
Often confused with
Cuboargyrite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside cuboargyrite
Minerals reported to co-occur with cuboargyrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgSbS₂
- Mohs hardness
- ~3
- Density
- 5.33 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In a hydrothermal assemblage
Where rockhounds find cuboargyrite
Classic worldwide localities
- Baberast, near Haslach, Central Black Forest, Germany
Field-hunting tip
Where it forms: In a hydrothermal assemblage. If you start seeing quartz, arsenopyrite in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cuboargyrite?+
Where is cuboargyrite found?+
Is cuboargyrite safe to handle?+
What rocks look like cuboargyrite?+
What minerals are found with cuboargyrite?+
What kind of rock does cuboargyrite form in?+
What is cuboargyrite used for?+
Find cuboargyrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
