Bismite is a rare secondary mineral that typically forms as a yellowish earthy crust or powdery aggregate resulting from the oxidation of native bismuth. It is found most commonly in the oxidized parts of hydrothermal veins and is prized by mineral collectors for its high density and associations with other bismuth-bearing species.
Is this bismite?
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 bismite with a known reference. Bismite sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: gray to yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine to dull, earthy.
- 4Match the color rangeCompare against the expected color range: green yellow, gray green, yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: earthy, pulverulent, scaly.
Often confused with
Bismite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bismite is noticeably harder (Mohs 4.5 vs. 2.5-3.5); luster reads subadamantine to dull, earthy on Bismite and vitreous, waxy, may be dull to earthy on Bismutite.
How to tell apart: Streak differs, so Bismite leaves gray to yellow, Bindheimite leaves white, yellowish white; luster reads subadamantine to dull, earthy on Bismite and resinous, dull, earthy on Bindheimite.
Often found alongside bismite
Minerals reported to co-occur with bismite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Bi₂O₃
- Mohs hardness
- 4.5
- Density
- 8.64-9.22 g/cm³
- Streak
- Gray to yellow
- Luster
- Subadamantine to dull, earthy
- Transparency
- Transparent in very small fragments
- Crystal system
- Monoclinic
- Crystal habit
- Earthy, pulverulent, scaly
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An oxidation product of bismuth
Where rockhounds find bismite
Classic worldwide localities
- Harding mine, Dixon, Taos Co., New Mexico, USA
- Victor mine, Rincon, and in a number of the pegmatites at Pala, San Diego Co., and near Baker, San Bernardino Co., California, USA
- Missouri mine, Park Co., Colorado, USA
- Colavi, at Tazna, and Llallagua, Bolivia
- Ebisu mine, Gifu Prefecture, Japan
Field-hunting tip
Where it forms: An oxidation product of bismuth. If you start seeing bismuth, bismutite, cassiterite in float, you are in the right ground. Typical habit: earthy, pulverulent, scaly. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bismite?+
Where is bismite found?+
Is bismite safe to handle?+
What rocks look like bismite?+
What minerals are found with bismite?+
What kind of rock does bismite form in?+
What is bismite used for?+
Find bismite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
