Sylvanite is a rare gold-silver telluride characterized by its unique graphic, bladed crystal habit that resembles ancient cuneiform or scribbling. It is almost exclusively found in low-temperature hydrothermal gold-telluride deposits and is considered a significant but uncommon ore of gold.
Is this sylvanite?
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 sylvanite with a known reference. Sylvanite 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. Sylvanite leaves a gray streak.
- 3Read the lusterHold the specimen under a strong light. Sylvanite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: silver-white, steel-gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed crystals, skeletal growths, massive.
Often confused with
Sylvanite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Sylvanite leaves gray, Calaverite leaves yellowish-green.
How to tell apart: Streak differs, so Sylvanite leaves gray, Krennerite leaves yellowish-grey.
How to tell apart: Streak differs, so Sylvanite leaves gray, Petzite leaves iron-black.
Often found alongside sylvanite
Minerals reported to co-occur with sylvanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Au,Ag)₂Te₄
- Mohs hardness
- 1.5-2
- Density
- 8.1-8.2 g/cm³
- Colors
- Streak
- Gray
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Bladed Crystals, Skeletal Growths, Massive
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector, Ore of Gold
- Host rock
- Epithermal Hydrothermal Veins
- Typical price
- $20-150 thumbnail, $200-800 cabinet
Where rockhounds find sylvanite
3 mapped spotsClassic worldwide localities
- Crippled Creek, Colorado, USA
- Baia de Aries, Romania
- Kalgoorlie, Western Australia
- Nagyág, Romania
Field-hunting tip
Look in epithermal hydrothermal veins country, the host setting where sylvanite typically forms. If you start seeing gold, petzite, fluorite in float, you are in the right ground. Field specimens usually show a bladed crystals, skeletal growths, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah. Start trip planning there.
Common questions
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Find sylvanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
