Manganohörnesite is a rare manganese-dominant member of the vivianite group often appearing as delicate, pale pink prismatic crystal aggregates. It is predominantly found in metamorphosed manganese ore deposits and requires careful handling due to its arsenic content and soft, fragile structure.
Is this manganohörnesite?
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 manganohörnesite with a known reference. Manganohörnesite sits at Mohs 1, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: stellate.
Often confused with
Manganohörnesite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside manganohörnesite
Minerals reported to co-occur with manganohörnesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn₃(AsO₄)₂·8H₂O
- Mohs hardness
- 1
- Density
- 2.64 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Stellate
- Cleavage
- Perfect on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- hydrothermal veins in metamorphic manganese deposits
Where rockhounds find manganohörnesite
Classic worldwide localities
- Langban, varmland, Sweden (type locality)
Field-hunting tip
Where it forms: hydrothermal veins in metamorphic manganese deposits. If you start seeing hedyphane, hausmannite, barite in float, you are in the right ground. Typical habit: stellate. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify manganohörnesite?+
Where is manganohörnesite found?+
Is manganohörnesite safe to handle?+
What rocks look like manganohörnesite?+
What minerals are found with manganohörnesite?+
What kind of rock does manganohörnesite form in?+
What is manganohörnesite used for?+
Find manganohörnesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
