Joséite-A is a rare bismuth telluride sulfide that typically occurs as metallic, lead-gray tabular crystals or foliated masses. It is most often found within hydrothermal gold deposits, frequently associated with other rare tellurides and native bismuth. Collectors usually prize it for its association with native gold and its distinct metallic luster.
Is this joséite-a?
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 joséite-a with a known reference. Joséite-A sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Joséite-A leaves a black-gray streak.
- 3Read the lusterHold the specimen under a strong light. Joséite-A typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, lead-gray, steel-gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: tabular crystals, foliated masses, or lamellar grains.
Often confused with
Joséite-A vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Joséite-A leaves black-gray, Bismuthinite leaves lead-gray.
How to tell apart: Streak differs — Joséite-A leaves black-gray, Tetradymite leaves lead-gray.
How to tell apart: Streak differs — Joséite-A leaves black-gray, Tellurobismuthite leaves lead-gray.
Often found alongside joséite-a
Minerals reported to co-occur with joséite-a. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi₄TeS₂
- Mohs hardness
- 1.5-2
- Density
- 8.3-8.5 g/cm³
- Streak
- Black-gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Tabular Crystals, Foliated Masses, Or Lamellar Grains
- Cleavage
- Perfect Basal
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Gold-bearing Quartz Veins
- Typical price
- $50-300 per small specimen depending on matrix and rarity
Where rockhounds find joséite-a
Classic worldwide localities
- São José, Minas Gerais, Brazil
- Berezovskoye, Ural Mountains, Russia
- Moctezuma, Sonora, Mexico
- Reichenstein, Silesia, Poland
Field-hunting tip
Look in hydrothermal gold-bearing quartz veins country — that is the host setting where joséite-a typically forms. If you start seeing gold, bismuthinite, tetradymite in float, you are in the right ground. Field specimens usually show a tabular crystals, foliated masses, or lamellar grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify joséite-a?+
Where is joséite-a found?+
How much is joséite-a worth?+
Is joséite-a safe to handle?+
What rocks look like joséite-a?+
What minerals are found with joséite-a?+
What kind of rock does joséite-a form in?+
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Find joséite-a on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
