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, 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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