Kostovite is a rare gold-copper telluride mineral typically found in epithermal ore deposits. Collectors primarily seek it as an obscure species associated with copper-rich precious metal assemblages, where it often appears as inconspicuous metallic grains or small masses.
Is this kostovite?
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 kostovite with a known reference. Kostovite sits at Mohs 2-2.5, 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 white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: microscopic crystals.
Often confused with
Kostovite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kostovite leaves black, Calaverite leaves greenish to yellowish gray.
How to tell apart: Streak differs, so Kostovite leaves black, Krennerite leaves greenish gray; luster reads metallic on Kostovite and very high metallic on Krennerite.
How to tell apart: Streak differs, so Kostovite leaves black, Sylvanite leaves steel-gray to silver-white.
Often found alongside kostovite
Minerals reported to co-occur with kostovite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AuCuTe₄
- Mohs hardness
- 2-2.5
- Density
- 8.43 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Microscopic crystals
- Cleavage
- Distinct in one direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- From gold- and tellurium-bearing replacement copper deposits (Chelopech, Bulgaria; Campbell mine, Arizona, USA)
Where rockhounds find kostovite
Classic worldwide localities
- Campbell mine, Bisbee, Cochise Co., Arizona, and at Buckeye Gulch, near Leadville, Lake Co., Colorado, USA
- Chelopech deposit, Sofia, Bulgaria (type locality)
- Kochbulak gold deposit, Chatkal-Kuramin Mountains, eastern Uzbekistan
- Guilaizhuang gold deposit, Shandong Province, China
- Ashanti gold deposit, Obuasi, Ghana
Field-hunting tip
Where it forms: From gold- and tellurium-bearing replacement copper deposits (Chelopech, Bulgaria; Campbell mine, Arizona, USA). If you start seeing kesterite, tellurium, chalcopyrite 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 kostovite?+
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Is kostovite safe to handle?+
What rocks look like kostovite?+
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Find kostovite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
