Baumstarkite is a rare monoclinic dimorph of the more common trigonal pyrargyrite. It is typically found in low-temperature hydrothermal silver deposits where it forms small, metallic, greyish-black crystals that are difficult to distinguish from other silver sulfosalts without X-ray diffraction.
Is this baumstarkite?
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 baumstarkite with a known reference. Baumstarkite sits at Mohs ~2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: grayish red to grayish black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: iron black, grayish black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: inclusions, tabular.
Often confused with
Baumstarkite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Baumstarkite leaves grayish red to grayish black, Pyrargyrite leaves purplish red; luster reads metallic on Baumstarkite and adamantine on Pyrargyrite.
How to tell apart: Streak differs, so Baumstarkite leaves grayish red to grayish black, Proustite leaves vermilion; luster reads metallic on Baumstarkite and adamantine on Proustite.
How to tell apart: Streak differs, so Baumstarkite leaves grayish red to grayish black, Stephanite leaves iron-black.
Often found alongside baumstarkite
Minerals reported to co-occur with baumstarkite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₃Sb₃S₆
- Mohs hardness
- ~2.5
- Density
- 5.33 g/cm³
- Colors
- Streak
- Grayish red to grayish black
- Luster
- Metallic
- Transparency
- Opaque, transparent on thin edges
- Crystal system
- Triclinic
- Crystal habit
- Inclusions, tabular
- Cleavage
- Perfect on {001}, less perfect on {100}
- Rarity
- Rare
- Uses
- Collector, Scientific study
- Host rock
- Of hydrothermal hypogene origin coating miargyrite (Peru); in an epithermal gold-silver quartz vein cutting black mudstone (Japan)
Where rockhounds find baumstarkite
Classic worldwide localities
- San Genaro mine, Huancavelica Department, Peru (type locality), Japan
Field-hunting tip
Where it forms: Of hydrothermal hypogene origin coating miargyrite (Peru); in an epithermal gold-silver quartz vein cutting black mudstone (Japan). If you start seeing miargyrite, pyrargyrite, stannite in float, you are in the right ground. Typical habit: inclusions, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify baumstarkite?+
Where is baumstarkite found?+
Is baumstarkite safe to handle?+
What rocks look like baumstarkite?+
What minerals are found with baumstarkite?+
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Find baumstarkite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
