Gananite is a rare bismuth halide that forms brown to black irregular aggregates. It occurs in wolframite-bearing quartz veins. Associated minerals include bismuth, bismuthinite and pyrite. It was first described from Ganan area, Laikeng district, southern Jiangxi Province, China.
Is this gananite?
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 gananite with a known reference. Gananite 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. Gananite leaves a dark gray streak.
- 3Read the lusterHold the specimen under a strong light. Gananite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: brown, black, greenish black.
- 5Look at form & habitCrystal system: cubic. Typical habit: in irregular aggregates.
Often confused with
Gananite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Sillimanite is the harder of the two (Mohs 6.5-7.5 vs. 3); streak differs, so Gananite leaves dark gray, Sillimanite leaves white; luster reads resinous on Gananite and vitreous on Sillimanite.
How to tell apart: Bismite is the harder of the two (Mohs 4.5 vs. 3); streak differs, so Gananite leaves dark gray, Bismite leaves gray to yellow; luster reads resinous on Gananite and subadamantine to dull to earthy on Bismite.
Often found alongside gananite
Minerals reported to co-occur with gananite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiF₃
- Mohs hardness
- 3
- Density
- 8.928 g/cm³
- Colors
- Streak
- Dark Gray
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- In Irregular Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
Where rockhounds find gananite
Classic worldwide localities
- Gana, China
Field-hunting tip
Look in hydrothermal veins country, the host setting where gananite typically forms. If you start seeing quartz, muscovite, bismuthinite in float, you are in the right ground. Field specimens usually show a in irregular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find gananite on the map
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