Goldfieldite is a rare tellurium-rich member of the tetrahedrite group, typically appearing as metallic, steel-gray to black tetrahedral crystals or massive aggregates. It is primarily found in epithermal gold-telluride deposits, often associated with other rare tellurium-bearing minerals and quartz.
Is this goldfieldite?
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 goldfieldite with a known reference. Goldfieldite sits at Mohs 3-3.5, 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: dark lead gray, iron black.
- 5Look at form & habitCrystal system: cubic. Typical habit: encrustations, massive.
Often confused with
Goldfieldite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside goldfieldite
Minerals reported to co-occur with goldfieldite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Cu₄□₂)Cu₆Te₄S₁₃
- Mohs hardness
- 3-3.5
- Density
- 4.95 g/cm³
- Colors
- Dark lead grayIron black
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Encrustations, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific study
- Host rock
- In epithermal gold-bearing veins; less commonly in porphyry copper and volcanogenic massive sulfide deposits
Where rockhounds find goldfieldite
Classic worldwide localities
- Goldfield, Esmeralda Co., in the Mohawk (type locality) and Claremont mines, Nevada, USA
- Tramway mine, Butte, Silver Bow Co., Montana, USA
- Campbell mine, Bisbee, Cochise Co., Arizona, USA
- Sweethome mine, Lake City, Hinsdale Co., Colorado, USA
- Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico
- El Indio mine, El Indio-Tambo district, east of La Serena, Coquimbo, Chile
Field-hunting tip
Where it forms: In epithermal gold-bearing veins; less commonly in porphyry copper and volcanogenic massive sulfide deposits. If you start seeing marcasite, famatinite, tennantite in float, you are in the right ground. Typical habit: encrustations, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify goldfieldite?+
Where is goldfieldite found?+
Is goldfieldite safe to handle?+
What rocks look like goldfieldite?+
What minerals are found with goldfieldite?+
What kind of rock does goldfieldite form in?+
What is goldfieldite used for?+
Find goldfieldite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
