Ludlockite is a rare lead-iron arsenate that typically forms delicate, needle-like acicular crystals or fibrous sprays. It is most famous for its occurrence in the Tsumeb Mine in Namibia, where it displays a vibrant, characteristic orange-red hue.
Is this ludlockite?
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 ludlockite with a known reference. Ludlockite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale brown.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine.
- 4Match the color rangeCompare against the expected color range: copper red.
- 5Look at form & habitCrystal system: triclinic. Typical habit: acicular.
Often confused with
Ludlockite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Carminite is the harder of the two (Mohs 3.5 vs. 1.5-2); streak differs, so Ludlockite leaves pale brown, Carminite leaves reddish yellow; luster reads subadamantine on Ludlockite and vitreous, pearly on cleavages on Carminite.
How to tell apart: Mimetite is the harder of the two (Mohs 3.5-4 vs. 1.5-2); streak differs, so Ludlockite leaves pale brown, Mimetite leaves white; luster reads subadamantine on Ludlockite and resinous to subadamantine on Mimetite.
Often found alongside ludlockite
Minerals reported to co-occur with ludlockite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- PbFe₄As₁₀O₂₂
- Mohs hardness
- 1.5-2
- Density
- 4.33-4.40 g/cm³
- Colors
- Streak
- Pale brown
- Luster
- Subadamantine
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Acicular
- Cleavage
- Perfect micaceous on {011}, perfect on {021}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In sulfide ore from a complex polymetallic hydrothermal ore deposit (Tsumeb, Namibia)
Where rockhounds find ludlockite
Classic worldwide localities
- Tsumeb, Namibia
- Laurium, Greece, in slag
- One km north of Campiglia, Tuscany, Italy, in slag
- Zarehehuran, near Takap, Takht-e-Suleiman massif, Azerbaijan
Field-hunting tip
Where it forms: In sulfide ore from a complex polymetallic hydrothermal ore deposit (Tsumeb, Namibia). If you start seeing zincian siderite, tennantite, chalcocite in float, you are in the right ground. Typical habit: acicular. Train your eye for that shape before scanning the outcrop.
Common questions
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Find ludlockite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
