Thorneite is an extremely rare lead sulfate-carbonate mineral typically found as a secondary mineral in old lead smelting slags. It usually forms small, transparent, tabular crystals that can be difficult to distinguish from other lead-bearing secondary minerals without chemical analysis.
Is this thorneite?
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 thorneite with a known reference. Thorneite 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: pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, clusters.
Often confused with
Thorneite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Thorneite leaves pale yellow, Anglesite leaves white.
How to tell apart: Cerussite is the harder of the two (Mohs 3-3.5 vs. 2); streak differs, so Thorneite leaves pale yellow, Cerussite leaves white.
Often found alongside thorneite
Minerals reported to co-occur with thorneite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Pb₆(Te₂O₁₀)(CO₃)Cl₂(H₂O)
- Mohs hardness
- 2
- Density
- 6.790 g/cm³
- Colors
- Streak
- Pale yellow
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, clusters
- Cleavage
- Good on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary phase on fracture surfaces and in small vugs in quartz veins
Where rockhounds find thorneite
Classic worldwide localities
- Bird Nest drift, southwest flank of Otto Mountain, ~2 km northwest of Baker, San Bernardino County, California, USA
Field-hunting tip
Where it forms: A secondary phase on fracture surfaces and in small vugs in quartz veins. If you start seeing acanthite, cerussite, gold in float, you are in the right ground. Typical habit: tabular crystals, clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify thorneite?+
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Find thorneite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
