Cervelleite is an extremely rare silver telluride sulfide typically found as tiny, microscopic inclusions within other silver minerals. It is primarily identified through laboratory analysis and is highly sought after by advanced mineral collectors for its chemical rarity.
Is this cervelleite?
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 cervelleite with a known reference. Cervelleite sits at Mohs 1.5, 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: gray, black.
- 5Look at form & habitCrystal system: cubic. Typical habit: microscopic crystals.
Often confused with
Cervelleite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Cervelleite leaves black, Hessite leaves light gray.
How to tell apart: Petzite is the harder of the two (Mohs 2.5-3 vs. 1.5); streak differs, so Cervelleite leaves black, Petzite leaves grayish black.
Often found alongside cervelleite
Minerals reported to co-occur with cervelleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₄TeS
- Mohs hardness
- 1.5
- Density
- 8.53 g/cm³
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In fracture fillings in highly altered and silicified rhyolite vitrophyre in a hydrothermal Au–Te deposit
Where rockhounds find cervelleite
Classic worldwide localities
- Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico (type locality)
Field-hunting tip
Where it forms: In fracture fillings in highly altered and silicified rhyolite vitrophyre in a hydrothermal Au–Te deposit. If you start seeing silver, acanthite, hessite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify cervelleite?+
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Find cervelleite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
