Manganlotharmeyerite is a rare member of the Tsumcorite group typically found in oxidized hydrothermal ore deposits. It is best identified by its distinct yellowish-orange prismatic crystals and close association with other secondary manganese and arsenic-bearing minerals.
Is this manganlotharmeyerite?
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 manganlotharmeyerite with a known reference. Manganlotharmeyerite 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: light brown.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: brownish red, dark reddish orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates, platy.
Often confused with
Manganlotharmeyerite 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 Manganlotharmeyerite leaves light brown, Tsumcorite leaves yellow; luster reads adamantine on Manganlotharmeyerite and vitreous on Tsumcorite.
How to tell apart: Streak differs, so Manganlotharmeyerite leaves light brown, Lotharmeyerite leaves pale orange to yellow-orange; luster reads adamantine on Manganlotharmeyerite and vitreous on Lotharmeyerite.
Often found alongside manganlotharmeyerite
Minerals reported to co-occur with manganlotharmeyerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMn³⁺₂(AsO₄)₂(OH)₂
- Mohs hardness
- 3
- Density
- 3.77 g/cm³
- Colors
- Brownish redDark reddish orange
- Streak
- Light brown
- Luster
- Adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates, platy
- Cleavage
- Distinct on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In discordant veinlets formed by late-stage remobilization of arsenic during retrograde metamorphism of a carbonate-hosted, syngenetic exhalative massive braunite deposit
Where rockhounds find manganlotharmeyerite
Classic worldwide localities
- Starlera Fe-Mn deposit, Val Ferrera, eastern Swiss Alps
Field-hunting tip
Where it forms: In discordant veinlets formed by late-stage remobilization of arsenic during retrograde metamorphism of a carbonate-hosted, syngenetic exhalative massive braunite deposit. If you start seeing calcite, tilasite, ailaufite in float, you are in the right ground. Typical habit: aggregates, platy. Train your eye for that shape before scanning the outcrop.
Common questions
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Find manganlotharmeyerite on the map
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