Mixite is a rare secondary bismuth-copper arsenate mineral known for forming delicate, needle-like radial sprays. It is typically found in the oxidation zones of ore deposits where bismuth and copper minerals have weathered. Collectors prize it for its vibrant green to blue-green color and aesthetic, tufted habit.
Is this mixite?
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 mixite with a known reference. Mixite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale bluish green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, silky in aggregates.
- 4Match the color rangeCompare against the expected color range: white, blue green, yellow green, light blue, light green.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular, encrustations, radial.
Often confused with
Mixite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous, silky in aggregates on Mixite and adamantine to vitreous; silky if fibrous; dull to earthy if massive on Malachite.
How to tell apart: Streak differs, so Mixite leaves pale bluish green, Clinoclase leaves bluish green.
How to tell apart: Mixite is noticeably harder (Mohs 3-4 vs. ~2).
Often found alongside mixite
Minerals reported to co-occur with mixite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BiCu₆(AsO₄)₃(OH)₆·3H₂O
- Mohs hardness
- 3-4
- Density
- 3.79-3.83 g/cm³
- Streak
- Pale bluish green
- Luster
- Vitreous, silky in aggregates
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular, encrustations, radial
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- An uncommon secondary mineral in the oxidized zone of copper deposits
Where rockhounds find mixite
Classic worldwide localities
- Mammoth and other mines, Tintic district, Juab Co., and at the Gold Hill mine, Tooele Co., Utah, USA
- Majuba Hill mine, Antelope district, Pershing Co., Nevada, USA
- Mammoth-St. Anthony mine, Tiger, Pinal Co., and at the Joe Shaft, Tombstone, Cochise Co., Arizona, USA
- Granite Gap, San Simon district, Hidalgo Co., New Mexico, USA
- Geister vein, Werner mine, Jáchymov (Joachimsthal), Czech Republic
- Wheals Owles and Edwards, St. Just, and several other mines in Cornwall, England
Field-hunting tip
Where it forms: An uncommon secondary mineral in the oxidized zone of copper deposits. If you start seeing bismutite, smaltite, bismuth in float, you are in the right ground. Typical habit: acicular, encrustations, radial. Train your eye for that shape before scanning the outcrop.
Common questions
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Find mixite on the map
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