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 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Manganohörnesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Manganohörnesite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: pink, pale pink, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial clusters, crusts.
Often confused with
Manganohörnesite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Manganohörnesite is noticeably harder (Mohs 2 vs. 1); luster reads vitreous on Manganohörnesite and pearly on Hörnesite.
How to tell apart: Streak differs — Manganohörnesite leaves white, Vivianite leaves white to light blue.
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
- (Mn,Mg)₃(AsO₄)₂·8H₂O
- Mohs hardness
- 2
- Density
- 2.8 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Radial Clusters, Crusts
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Metamorphic Manganese Deposits
- Typical price
- $50-300 per specimen depending on size and quality
Where rockhounds find manganohörnesite
Classic worldwide localities
- Långban, Sweden
- Sterling Hill, New Jersey, USA
- Broken Hill, Australia
Field-hunting tip
Look in hydrothermal veins in metamorphic manganese deposits country — that is the host setting where manganohörnesite typically forms. If you start seeing hedyphane, hausmannite, barite in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial clusters, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify manganohörnesite?+
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Find manganohörnesite on the map
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