Psilomelane, now scientifically known as romanechite, is a hard, black manganese oxide typically found in botryoidal or stalactitic forms. It is easily identified by its smooth, mammillary surface texture and heavy weight. Collectors highly prize high-quality, polished botryoidal specimens for their unique, grape-like clusters.
Is this psilomelane?
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 psilomelane with a known reference. Psilomelane sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Psilomelane leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Psilomelane typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, bluish-black, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal, reniform, massive.
Often confused with
Psilomelane vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads submetallic on Psilomelane and metallic on Pyrolusite.
How to tell apart: Psilomelane is noticeably harder (Mohs 5-6 vs. 4); streak differs — Psilomelane leaves black, Manganite leaves dark reddish-brown.
How to tell apart: Streak differs — Psilomelane leaves black, Iron Ore leaves reddish-brown to black; luster reads submetallic on Psilomelane and metallic to submetallic on Iron Ore.
Often found alongside psilomelane
Minerals reported to co-occur with psilomelane. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ba,H₂O)₂Mn₅O₁₀
- Mohs hardness
- 5-6
- Density
- 4.7-5.1 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal, Reniform, Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Ore of Manganese
- Host rock
- Sedimentary Manganese Deposits, Hydrothermal Veins
- Typical price
- $10-50 thumbnail, $50-200 display specimen
Where rockhounds find psilomelane
4 mapped spotsClassic worldwide localities
- Romanèche-Thorins, France
- Sterling Hill, New Jersey
- Germany
- Mexico
- Arizona, USA
Field-hunting tip
Look in sedimentary manganese deposits, hydrothermal veins country — that is the host setting where psilomelane typically forms. If you start seeing pyrolusite, manganite, barite in float, you are in the right ground. Field specimens usually show a botryoidal, reniform, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, Idaho, West Virginia — start trip planning there.
Common questions
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Find psilomelane on the map
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