Paraguanajuatite is a rare selenium-rich bismuth selenide typically found in hydrothermal vein deposits. It is best identified by its metallic lead-gray color, perfect cleavage, and distinct association with other bismuth-bearing minerals in volcanic or epithermal environments.
Is this paraguanajuatite?
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 paraguanajuatite with a known reference. Paraguanajuatite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Paraguanajuatite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Paraguanajuatite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, steel-gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: lamellar or granular aggregates.
Often confused with
Paraguanajuatite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Paraguanajuatite leaves black, Tetradymite leaves lead-gray.
How to tell apart: Streak differs — Paraguanajuatite leaves black, Guanajuatite leaves lead-gray.
How to tell apart: Streak differs — Paraguanajuatite leaves black, Bismuthinite leaves lead-gray.
Often found alongside paraguanajuatite
Minerals reported to co-occur with paraguanajuatite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi₂Se₂Se
- Mohs hardness
- 2-2.5
- Density
- 7.5 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Lamellar or Granular Aggregates
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find paraguanajuatite
Classic worldwide localities
- Guanajuato, Mexico
- Pacajake, Bolivia
- Sierra de Cacheuta, Argentina
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where paraguanajuatite typically forms. If you start seeing calcite, quartz, guanajuatite in float, you are in the right ground. Field specimens usually show a lamellar or granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find paraguanajuatite on the map
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