Neltnerite is a rare manganese silicate mineral that belongs to the braunite group, appearing as small, dark, submetallic crystals. It is primarily identified by its occurrence in specific manganese-rich metamorphic environments, most notably in the Tachgagalt mine in Morocco. Collectors should look for its distinct tetragonal crystal habit when evaluating potential specimens.
Is this neltnerite?
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 neltnerite with a known reference. Neltnerite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Neltnerite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Neltnerite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: equant to dipyramidal crystals.
Often confused with
Neltnerite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside neltnerite
Minerals reported to co-occur with neltnerite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMn⁶⁺₆SiO₁₂
- Mohs hardness
- 6
- Density
- 4.87 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Equant to Dipyramidal Crystals
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Manganese Deposits
- Typical price
- $50-300 per specimen depending on crystal quality
Where rockhounds find neltnerite
Classic worldwide localities
- Tachgagalt, Anti-Atlas, Morocco
Field-hunting tip
Look in metamorphosed manganese deposits country — that is the host setting where neltnerite typically forms. If you start seeing braunite, hausmannite, bixbyite in float, you are in the right ground. Field specimens usually show a equant to dipyramidal crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find neltnerite on the map
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