Heterogenite is a cobalt oxyhydroxide often found in the weathered zones of cobalt-rich deposits. It is most recognized by its characteristic botryoidal or kidney-like habit and its deep black, submetallic luster, frequently coating other secondary copper and cobalt minerals.
Is this heterogenite?
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 heterogenite with a known reference. Heterogenite 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: dark brown.
- 3Read the lusterHold the specimen under a strong light. Luster: dull to vitreous.
- 4Match the color rangeCompare against the expected color range: black, blackish brown, reddish brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: botryoidal, reniform, massive, earthy.
Often confused with
Heterogenite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Heterogenite leaves dark brown, Psilomelane leaves brownish black; luster reads dull to vitreous on Heterogenite and submetallic on Psilomelane.
How to tell apart: Streak differs, so Heterogenite leaves dark brown, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads dull to vitreous on Heterogenite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
How to tell apart: Streak differs, so Heterogenite leaves dark brown, Limonite leaves yellowish-brown; luster reads dull to vitreous on Heterogenite and submetallic to earthy on Limonite.
Often found alongside heterogenite
Minerals reported to co-occur with heterogenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CoO(OH)
- Mohs hardness
- 3-5
- Density
- 4.4-4.8 g/cm³
- Streak
- Dark brown
- Luster
- Dull to vitreous
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Botryoidal, reniform, massive, earthy
- Cleavage
- In crystals, {0001}
- Rarity
- Uncommon
- Uses
- Collector, Cobalt ore
- Host rock
- A weathering product of smaltite (Schneeberg, Germany); an alteration product of linnaeite, constituting an important ore of cobalt (Shaba Province, Congo)
Where rockhounds find heterogenite
Classic worldwide localities
- Goodsprings, Clark Co., Nevada, USA
- Schneeberg, Saxony, Germany
- Anton mine, Heubachtal, and Wittichen, Black Forest, Germany
- Richelsdorf, Hesse, Germany
- Congo (Zaire), in Katanga (Shaba) Province, in the Star of the Congo mine, near Lubumbashi
- Tsumeb, Namibia
Field-hunting tip
Where it forms: A weathering product of smaltite (Schneeberg, Germany); an alteration product of linnaeite, constituting an important ore of cobalt (Shaba Province, Congo). If you start seeing smaltite, pharmacosiderite, calcite in float, you are in the right ground. Typical habit: botryoidal, reniform, massive, earthy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify heterogenite?+
Where is heterogenite found?+
Is heterogenite safe to handle?+
What rocks look like heterogenite?+
What minerals are found with heterogenite?+
What kind of rock does heterogenite form in?+
What is heterogenite used for?+
Find heterogenite on the map
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