Aurostibite is a rare gold-antimony mineral that typically forms as microscopic grains in gold-bearing quartz veins or as overgrowths on native gold. It is highly sought by mineral collectors specializing in gold species, often requiring microscopic study due to its occurrence as small, non-descript inclusions in massive ore samples.
Is this aurostibite?
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 aurostibite with a known reference. Aurostibite 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. Streak: bronze.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: lead gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains, massive, interstitial fillings.
Often confused with
Aurostibite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Pyrite is the harder of the two (Mohs 6-6.5 vs. 3); streak differs, so Aurostibite leaves bronze, Pyrite leaves greenish black to brownish black.
How to tell apart: Aurostibite is noticeably harder (Mohs 3 vs. 2); streak differs, so Aurostibite leaves bronze, Stibnite leaves lead-gray.
How to tell apart: Sperrylite is the harder of the two (Mohs 6-7 vs. 3); streak differs, so Aurostibite leaves bronze, Sperrylite leaves black.
Often found alongside aurostibite
Minerals reported to co-occur with aurostibite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AuSb₂
- Mohs hardness
- 3
- Density
- 9.98 g/cm³
- Colors
- Streak
- Bronze
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral grains, massive, interstitial fillings
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In hydrothermal gold-quartz veins, in portions deficient in sulfur and containing other antimony minerals
Where rockhounds find aurostibite
Classic worldwide localities
- Giant Yellowknife mine, Yellowknife, Northwest Territories (type locality), Canada
- Chesterville mine, Larder Lake and the Hemlo gold deposit, Thunder Bay district, Ontario, Canada
- Krásná Hora, near Milesov, Czech Republic
- Viges Au–Sb deposit, Creuse, France
- Langsele deposit, Skellefte district, Sweden
- Kallisalo gold deposit, Seinajoki district, western Finland
Field-hunting tip
Where it forms: In hydrothermal gold-quartz veins, in portions deficient in sulfur and containing other antimony minerals. If you start seeing gold, freibergite, stibnite in float, you are in the right ground. Typical habit: anhedral grains, massive, interstitial fillings. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify aurostibite?+
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Is aurostibite safe to handle?+
What rocks look like aurostibite?+
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Find aurostibite on the map
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