Lotharmeyerite is a rare secondary mineral typically found in oxidized zones of arsenic-rich base metal deposits. It often forms vibrant orange to yellow bladed crystals or crusts that contrast beautifully against host rocks like smithsonite or limonite.
Is this lotharmeyerite?
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 lotharmeyerite with a known reference. Lotharmeyerite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale orange to yellow-orange.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark reddish orange, reddish brown, red orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: druse, encrustations.
Often confused with
Lotharmeyerite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Tsumcorite is the harder of the two (Mohs 4.5 vs. ~3); streak differs, so Lotharmeyerite leaves pale orange to yellow-orange, Tsumcorite leaves yellow.
How to tell apart: Lotharmeyerite is noticeably harder (Mohs ~3 vs. 2); streak differs, so Lotharmeyerite leaves pale orange to yellow-orange, Reevesite leaves yellow; luster reads vitreous on Lotharmeyerite and pearly on Reevesite.
How to tell apart: Conichalcite is the harder of the two (Mohs 4.5 vs. ~3); streak differs, so Lotharmeyerite leaves pale orange to yellow-orange, Conichalcite leaves green.
Often found alongside lotharmeyerite
Minerals reported to co-occur with lotharmeyerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaZn₂(AsO₄)₂·2H₂O
- Mohs hardness
- ~3
- Density
- 4.23 g/cm³
- Colors
- Streak
- Pale orange to yellow-orange
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Druse, encrustations
- Cleavage
- On {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In the oxidized zone of an arsenic-rich polymetallic base-metal deposit
Where rockhounds find lotharmeyerite
Classic worldwide localities
- Ojuela mine, Mapimí, Durango, Mexico
Field-hunting tip
Where it forms: In the oxidized zone of an arsenic-rich polymetallic base-metal deposit. If you start seeing adamite, cryptomelane, chalcophanite in float, you are in the right ground. Typical habit: druse, encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify lotharmeyerite?+
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Is lotharmeyerite safe to handle?+
What rocks look like lotharmeyerite?+
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Find lotharmeyerite on the map
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