Montbrayite is a rare gold-telluride mineral typically found as massive aggregates within hydrothermal ore deposits. It is best identified by its high density and association with other telluride species, often requiring X-ray diffraction for definitive confirmation.
Is this montbrayite?
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 montbrayite with a known reference. Montbrayite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Montbrayite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Montbrayite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, pale yellow.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive, granular.
Often confused with
Montbrayite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Montbrayite leaves black, Petzite leaves iron-black.
How to tell apart: Streak differs — Montbrayite leaves black, Krennerite leaves yellowish-grey.
How to tell apart: Streak differs — Montbrayite leaves black, Calaverite leaves yellowish-green.
Often found alongside montbrayite
Minerals reported to co-occur with montbrayite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Au,Sb)₂Te₃
- Mohs hardness
- 2.5-3
- Density
- 9.9 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Gold-telluride Deposits
- Typical price
- $50-300 per small specimen
Where rockhounds find montbrayite
Classic worldwide localities
- Montbray Township, Quebec, Canada
- Kalgoorlie, Western Australia
- Salsigne, France
Field-hunting tip
Look in hydrothermal gold-telluride deposits country — that is the host setting where montbrayite typically forms. If you start seeing tellurobismutite, gold, pyrite in float, you are in the right ground. Field specimens usually show a massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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How much is montbrayite worth?+
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Find montbrayite on the map
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