Bernalite is a rare iron hydroxide mineral typically found as small, dark green pseudo-cubic crystals. Collectors primarily seek it from the oxidized portions of lead-zinc deposits, where it is often associated with other rare oxidation products.
Is this bernalite?
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 bernalite with a known reference. Bernalite sits at Mohs 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: apple-green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to adamantine when fresh; resinous on crystal surfaces.
- 4Match the color rangeCompare against the expected color range: yellow green, dark bottle green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: pseudo-cubic crystals, tabular crystals.
Often confused with
Bernalite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bernalite is noticeably harder (Mohs 4 vs. 1.5-2); streak differs, so Bernalite leaves apple-green, Ludlockite leaves pale brown; luster reads vitreous to adamantine when fresh; resinous on crystal surfaces on Bernalite and subadamantine on Ludlockite.
How to tell apart: Goethite is the harder of the two (Mohs 5-5.5 vs. 4); streak differs, so Bernalite leaves apple-green, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads vitreous to adamantine when fresh; resinous on crystal surfaces on Bernalite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
Often found alongside bernalite
Minerals reported to co-occur with bernalite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe(OH)₃
- Mohs hardness
- 4
- Density
- 3.32 g/cm³
- Colors
- Yellow greenDark bottle green
- Streak
- Apple-green
- Luster
- Vitreous to adamantine when fresh; resinous on crystal surfaces
- Transparency
- Transparent to opaque due to goethite inclusions
- Crystal system
- Orthorhombic
- Crystal habit
- Pseudo-cubic crystals, tabular crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- On a museum specimen from a metamorphosed Pb-Zn deposit, probably from the surface oxidation zone
Where rockhounds find bernalite
Classic worldwide localities
- Proprietary mine, Broken Hill, New South Wales, Australia
- Clara mine, central Black Forest, Germany
Field-hunting tip
Where it forms: On a museum specimen from a metamorphosed Pb-Zn deposit, probably from the surface oxidation zone. If you start seeing goethite, coronadite in float, you are in the right ground. Typical habit: pseudo-cubic crystals, tabular crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find bernalite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
