Miguelromeroite is a rare manganese arsenate mineral found in the oxidized zones of ore deposits. It typically forms small, transparent yellow or orange crystals and is highly prized by micromounters and advanced mineral collectors.
Is this miguelromeroite?
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 miguelromeroite with a known reference. Miguelromeroite sits at Mohs ~4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale pink.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: orange-pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: equant to short prismatic crystals, often as crusts.
Often confused with
Miguelromeroite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside miguelromeroite
Minerals reported to co-occur with miguelromeroite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₅(AsO₃OH)₂(AsO₄)₂(H₂O)₄
- Mohs hardness
- ~4
- Density
- 3.69 g/cm³
- Colors
- Orange-pink
- Streak
- Very pale pink
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Equant to short prismatic crystals, often as crusts
- Cleavage
- Good on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In secondary oxidation zones of arsenic-rich base metal deposits
Where rockhounds find miguelromeroite
Classic worldwide localities
- San Judas Chimney, Ojuela mine, Mapimi, Durango, Mexico (type locality)
- Veta Negra mine, Tierra Amarilla, Copiapó Province, Chile, Japan
- Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA, Japan
- Gozaisho mine, Iwaki, Fukushima Prefecture, Honshu, Japan
Field-hunting tip
Where it forms: In secondary oxidation zones of arsenic-rich base metal deposits. If you start seeing arseniosiderite, ogdensburgite, chalcophanite in float, you are in the right ground. Typical habit: equant to short prismatic crystals, often as crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify miguelromeroite?+
Where is miguelromeroite found?+
Is miguelromeroite safe to handle?+
What rocks look like miguelromeroite?+
What minerals are found with miguelromeroite?+
What kind of rock does miguelromeroite form in?+
What is miguelromeroite used for?+
Find miguelromeroite on the map
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