Tenorite is a secondary copper oxide mineral typically found in the weathered oxidation zones of copper sulfide ore deposits. It is most commonly identified as a dull black, earthy, or metallic crust or powder coating other copper minerals like cuprite and malachite.
Is this tenorite?
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 tenorite with a known reference. Tenorite sits at Mohs 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: black, steel gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: earthy, massive, scaly.
Often confused with
Tenorite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Goethite is the harder of the two (Mohs 5-5.5 vs. 3.5); streak differs, so Tenorite leaves black, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads metallic on Tenorite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
How to tell apart: Streak differs, so Tenorite leaves black, Manganite leaves reddish brown to nearly black; luster reads metallic on Tenorite and submetallic on Manganite.
Often found alongside tenorite
Minerals reported to co-occur with tenorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CuO
- Mohs hardness
- 3.5
- Density
- 6.45 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque, transparent only in the thinnest scales
- Crystal system
- Monoclinic
- Crystal habit
- Earthy, massive, scaly
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Ore of copper
- Host rock
- Commonly in the oxidized zone of hydrothermal copper deposits; a volcanic sublimate
Where rockhounds find tenorite
2 mapped spotsClassic worldwide localities
- Copper Harbor, Keweenaw Co., Michigan, USA
- Darwin, Inyo Co., California, USA
- Bisbee, Cochise Co., Arizona, USA
- Vesuvius, Campania, and Etna, Sicily, Italy
- A number of mines in Gwennap, Redruth, St. Just, Cornwall, England
- Leadhills, Lanarkshire, Scotland
Field-hunting tip
Where it forms: Commonly in the oxidized zone of hydrothermal copper deposits; a volcanic sublimate. If you start seeing cuprite, copper, chrysocolla in float, you are in the right ground. Typical habit: earthy, massive, scaly. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arizona, Utah. Start trip planning there.
Common questions
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Find tenorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
