Massicot is a rare, soft secondary mineral that typically forms as an oxidation product of galena. It is most commonly found as earthy or scaly yellow crusts and coatings on lead ore specimens.
Is this massicot?
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 massicot with a known reference. Massicot sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy to dull.
- 4Match the color rangeCompare against the expected color range: yellow, reddish yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: earthy, massive, scaly.
Often confused with
Massicot vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Massicot leaves yellow, Litharge leaves red.
How to tell apart: Streak differs, so Massicot leaves yellow, Minium leaves yellow-orange; luster reads greasy to dull on Massicot and dull to slightly greasy on Minium.
How to tell apart: Streak differs, so Massicot leaves yellow, Sulfur leaves white; luster reads greasy to dull on Massicot and resinous on Sulfur.
Often found alongside massicot
Minerals reported to co-occur with massicot. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbO
- Mohs hardness
- 2
- Density
- 9.642 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Greasy to dull
- Transparency
- Translucent, transparent on thin edges
- Crystal system
- Orthorhombic
- Crystal habit
- Earthy, massive, scaly
- Cleavage
- Distinct on {100}; distinct on {010}
- Rarity
- Uncommon
- Uses
- Collector, Industrial (historical)
- Host rock
- As an oxidation product of galena, bournonite, boulangerite, and other lead-bearing minerals
Where rockhounds find massicot
Classic worldwide localities
- Cerro Gordo district, Inyo Co., and on Cucamonga Peak, San Bernardino Co., California, USA
- Tonopah-Belmont mine, Osborne district, at the Moon Anchor mine, Potter-Cramer property, and the Rat Tail claim, Vulture district, Maricopa Co., Arizona, USA
- Flux mine, Patagonia Mountains, Santa Cruz Co., Arizona, USA
- Freiberg, Saxony, at Greifenstein, Nassau, Germany
- Malmes, Gard, France
- Ally, Haute-Loire, France
Field-hunting tip
Where it forms: As an oxidation product of galena, bournonite, boulangerite, and other lead-bearing minerals. If you start seeing cerussite, litharge, minium in float, you are in the right ground. Typical habit: earthy, massive, scaly. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify massicot?+
Where is massicot found?+
Is massicot safe to handle?+
What rocks look like massicot?+
What minerals are found with massicot?+
What kind of rock does massicot form in?+
What is massicot used for?+
Find massicot on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
