Muthmannite is a rare silver-gold telluride often found in epithermal gold deposits. It is typically identified in massive form within hydrothermal quartz veins, characterized by its metallic luster and high density.
Is this muthmannite?
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 muthmannite with a known reference. Muthmannite sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Muthmannite leaves a grayish-white streak.
- 3Read the lusterHold the specimen under a strong light. Muthmannite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: pale yellow, tin-white, grayish-white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, granular, or anhedral grains.
Often confused with
Muthmannite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Muthmannite leaves grayish-white, Sylvanite leaves gray.
How to tell apart: Streak differs — Muthmannite leaves grayish-white, Calaverite leaves yellowish-green.
How to tell apart: Streak differs — Muthmannite leaves grayish-white, Petzite leaves iron-black.
Often found alongside muthmannite
Minerals reported to co-occur with muthmannite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgAuTe₂
- Mohs hardness
- 2.5
- Density
- 8.3 g/cm³
- Streak
- Grayish-white
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, Granular, Or Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-500 depending on specimen size and purity
Where rockhounds find muthmannite
Classic worldwide localities
- Sacaramb, Romania
- Kalgoorlie, Australia
- Crippled Creek, USA
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where muthmannite typically forms. If you start seeing gold, tellurides, quartz in float, you are in the right ground. Field specimens usually show a massive, granular, or anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find muthmannite on the map
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