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, so Paraguanajuatite leaves black, Tetradymite leaves lead-gray.
How to tell apart: Streak differs, so Paraguanajuatite leaves black, Guanajuatite leaves lead-gray.
How to tell apart: Streak differs, so 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, 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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