Coronadite is a dark, opaque lead manganese oxide typically found in the oxidized zones of ore deposits. It frequently forms distinctive botryoidal, fibrous, or massive aggregates that are hard to distinguish from other manganese oxides without analytical testing.
Is this coronadite?
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 coronadite with a known reference. Coronadite sits at Mohs 4.5-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish black.
- 3Read the lusterHold the specimen under a strong light. Luster: dull to submetallic.
- 4Match the color rangeCompare against the expected color range: black, grayish black, dark gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal, fibrous.
Often confused with
Coronadite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull to submetallic on Coronadite and submetallic on Psilomelane.
How to tell apart: Streak differs, so Coronadite leaves brownish black, Pyrolusite leaves black, bluish black; luster reads dull to submetallic on Coronadite and metallic on Pyrolusite.
How to tell apart: Hollandite is the harder of the two (Mohs 6 vs. 4.5-5); streak differs, so Coronadite leaves brownish black, Hollandite leaves black; luster reads dull to submetallic on Coronadite and metallic, splendent on Hollandite.
Often found alongside coronadite
Minerals reported to co-occur with coronadite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb(Mn₆Mn₂)O₁₆
- Mohs hardness
- 4.5-5
- Density
- 5.246-5.505 g/cm³
- Streak
- Brownish black
- Luster
- Dull to submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal, fibrous
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Ore of manganese
- Host rock
- A primary mineral in hydrothermal veins or from hot springs; of secondary origin in oxidized zones above manganese-bearing rocks; also in bedded sedimentary deposits
Where rockhounds find coronadite
Classic worldwide localities
- Coronado vein, Clifton-Morenci district, Greenlee Co., Arizona, USA
- Magma mine, Superior, Pinal Co., Arizona, USA
- Artillery Mountains, Mohave Co., Arizona, USA
- Luis Lopez district, Socorro Co., New Mexico, USA
- Talamantes district, Chihuahua, and in the Ojuela mine, Mapimí, Durango, Mexico
- Almalyskoye Pb–Zn deposit, Kurgashikan, Uzbekistan
Field-hunting tip
Where it forms: A primary mineral in hydrothermal veins or from hot springs; of secondary origin in oxidized zones above manganese-bearing rocks; also in bedded sedimentary deposits. If you start seeing hollandite, pyrolusite in float, you are in the right ground. Typical habit: botryoidal, fibrous. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify coronadite?+
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Find coronadite on the map
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