Manganoneptunite is a rare manganese-dominant member of the neptunite group, distinguished from common neptunite by its specific chemical composition. It typically forms sharp, lustrous black prismatic crystals associated with rare-earth minerals in alkaline pegmatites, often found in complex specimens from Mont Saint-Hilaire.
Is this manganoneptunite?
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 manganoneptunite with a known reference. Manganoneptunite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish red.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals.
Often confused with
Manganoneptunite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside manganoneptunite
Minerals reported to co-occur with manganoneptunite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KNa₂LiMn₂Ti₂Si₈O₂₄
- Mohs hardness
- 5-6
- Density
- 3.23 g/cm³
- Colors
- Streak
- Brownish red
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals
- Cleavage
- Distinct on {110}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Found in syenites and syenite pegmatites
Where rockhounds find manganoneptunite
Classic worldwide localities
- Lovozero Massif, Kola Peninsula, Russia (type locality)
Field-hunting tip
Where it forms: Found in syenites and syenite pegmatites. If you start seeing eudialyte, serandite, leifite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify manganoneptunite?+
Where is manganoneptunite found?+
What rocks look like manganoneptunite?+
What minerals are found with manganoneptunite?+
What kind of rock does manganoneptunite form in?+
What is manganoneptunite used for?+
Find manganoneptunite on the map
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