Minium is a rare secondary lead mineral formed by the oxidation of galena. It is most often found as a soft, earthy, or powdery coating on other lead ores and is famously known for its vivid orange-red color.
Is this minium?
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 minium with a known reference. Minium sits at Mohs 2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Minium leaves a orange-yellow streak.
- 3Read the lusterHold the specimen under a strong light. Minium typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: red, orange, bright red.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: massive, earthy, or as a pulverulent coating.
Often confused with
Minium vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Minium leaves orange-yellow, Cinnabar leaves scarlet; luster reads dull on Minium and adamantine on Cinnabar.
How to tell apart: Streak differs — Minium leaves orange-yellow, Realgar leaves orange-red; luster reads dull on Minium and resinous on Realgar.
How to tell apart: Iron Ore is the harder of the two (Mohs 5-6.5 vs. 2.5); streak differs — Minium leaves orange-yellow, Iron Ore leaves reddish-brown to black; luster reads dull on Minium and metallic to submetallic on Iron Ore.
Often found alongside minium
Minerals reported to co-occur with minium. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₃O₄
- Mohs hardness
- 2.5
- Density
- 8.9-9.1 g/cm³
- Colors
- Streak
- Orange-yellow
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Massive, Earthy, Or as A Pulverulent Coating
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Historical Pigment
- Host rock
- Oxidized Zones of Lead-bearing Ore Deposits
- Typical price
- $20-150 for small, high-quality specimens
Where rockhounds find minium
Classic worldwide localities
- Broken Hill, Australia
- Siegen, Germany
- Leadville, USA
- Laurion, Greece
Field-hunting tip
Look in oxidized zones of lead-bearing ore deposits country — that is the host setting where minium typically forms. If you start seeing galena, cerussite, anglesite in float, you are in the right ground. Field specimens usually show a massive, earthy, or as a pulverulent coating habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find minium on the map
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