Plumbogummite is a secondary mineral typically found as a coating or botryoidal crust in the oxidized zones of lead-bearing ore deposits. It is most prized by collectors for its vibrant blue or green spherical aggregates, often found pseudomorphing other crystals like pyromorphite.
Is this plumbogummite?
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 plumbogummite with a known reference. Plumbogummite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, resinous to dull.
- 4Match the color rangeCompare against the expected color range: white, gray, yellow, bluish green, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: colloform, stalactitic.
Often confused with
Plumbogummite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous, resinous to dull on Plumbogummite and resinous to subadamantine on Pyromorphite.
How to tell apart: Luster reads vitreous, resinous to dull on Plumbogummite and resinous to subadamantine on Mimetite.
Often found alongside plumbogummite
Minerals reported to co-occur with plumbogummite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbAl₃(PO₄)₂(OH)₅·H₂O
- Mohs hardness
- 4.5-5
- Density
- 4.01 g/cm³
- Streak
- White
- Luster
- Vitreous, resinous to dull
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Colloform, stalactitic
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- An uncommon secondary mineral in the oxidized zone of lead deposits
Where rockhounds find plumbogummite
Classic worldwide localities
- Canton mine, Cherokee Co., Georgia, USA
- Tyrone mine, Santa Rita, Grant Co., and the Mex-Tex mine, near Bingham, Hansonburg district, Socorro Co., New Mexico, USA
- Hahns Peak district, Routt Co., Colorado, USA
- Copper Cities deposit, Gila Co., Arizona, USA
- Huelgoat, Finistère, France
- Roughton Gill, Red Gill, Dry Gill, and other mines, Caldbeck Fells, Cumbria, England
Field-hunting tip
Where it forms: An uncommon secondary mineral in the oxidized zone of lead deposits. If you start seeing pyromorphite, mimetite, duftite in float, you are in the right ground. Typical habit: colloform, stalactitic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify plumbogummite?+
Where is plumbogummite found?+
Is plumbogummite safe to handle?+
What rocks look like plumbogummite?+
What minerals are found with plumbogummite?+
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Find plumbogummite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
