Maldonite is a rare intermetallic compound of gold and bismuth found primarily in hydrothermal quartz veins. It is notable for its distinct pinkish-white metallic luster, which quickly tarnishes to a duller yellow or brown when exposed to air.
Is this maldonite?
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 maldonite with a known reference. Maldonite 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. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: silver white, copper red, reddish white, black.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, octahedral crystals.
Often confused with
Maldonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Maldonite leaves black, Gold leaves yellow.
How to tell apart: Streak differs, so Maldonite leaves black, Tellurobismuthite leaves pale lead-gray.
How to tell apart: Streak differs, so Maldonite leaves black, Tetradymite leaves pale steel-gray.
Often found alongside maldonite
Minerals reported to co-occur with maldonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Au₂Bi
- Mohs hardness
- 1.5-2
- Density
- 15.46 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, octahedral crystals
- Cleavage
- Distinct on {001} and {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed below 373°C, under hydrothermal conditions in gold-quartz veins and stockworks, and calc-silicate skarns
Where rockhounds find maldonite
Classic worldwide localities
- Shotgun deposit, about 150 km north of Dillingham, and on the Pogo claims, 145 km southeast of Fairbanks, Alaska, USA
- Maldon, from Nuggety Reef (type locality), and in the Eagle Hawk mine, Union Reef, Victoria, Australia
- Kingsgate and from the Lucky Draw mine, New South Wales, Australia
- Salsigne gold deposit, 15 km north of Carcassone, Aude, and from Scoufour, Cantal, France
- Ortosa Au–Bi–Te deposit, Asturias, Spain
- Baita ??, Romania
Field-hunting tip
Where it forms: Formed below 373°C, under hydrothermal conditions in gold-quartz veins and stockworks, and calc-silicate skarns. If you start seeing gold, bismuth, bismuthinite in float, you are in the right ground. Typical habit: massive, octahedral crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify maldonite?+
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Find maldonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
