Stilpnomelane is a phyllosilicate mineral typically found in metamorphosed iron-rich rocks and low-grade metamorphic schists. It is easily recognized by its dark, bronzy to black color and distinctive platy or foliated habit, which resembles common micas but with a more brittle structure.
Is this stilpnomelane?
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 stilpnomelane with a known reference. Stilpnomelane sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Stilpnomelane leaves a yellowish-brown to greenish-black streak.
- 3Read the lusterHold the specimen under a strong light. Stilpnomelane typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black, bronze, greenish-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, foliated masses, radiating sprays.
Often confused with
Stilpnomelane vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Stilpnomelane leaves yellowish-brown to greenish-black, Biotite leaves white.
How to tell apart: Streak differs — Stilpnomelane leaves yellowish-brown to greenish-black, Chlorite leaves white.
How to tell apart: Streak differs — Stilpnomelane leaves yellowish-brown to greenish-black, Muscovite leaves white.
Often found alongside stilpnomelane
Minerals reported to co-occur with stilpnomelane. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K(Fe²⁺,Mg,Fe³⁺)₈(Si,Al)₁₂O₃₀(OH)₁₂·nH₂O
- Mohs hardness
- 3-4
- Density
- 2.7-3.0 g/cm³
- Streak
- Yellowish-brown to Greenish-black
- Luster
- Pearly
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Foliated Masses, Radiating Sprays
- Cleavage
- Perfect Basal
- Rarity
- Common
- Uses
- Collector
- Host rock
- Low to Medium Grade Metamorphic Rocks, Iron Formations
- Typical price
- $10-60 per specimen
Where rockhounds find stilpnomelane
1 mapped spotsClassic worldwide localities
- Czech Republic
- Canada
- Germany
- USA
- New Zealand
Field-hunting tip
Look in low to medium grade metamorphic rocks, iron formations country — that is the host setting where stilpnomelane typically forms. If you start seeing quartz, albite, magnetite in float, you are in the right ground. Field specimens usually show a platy crystals, foliated masses, radiating sprays habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Jersey — start trip planning there.
Common questions
How do you identify stilpnomelane?+
Where is stilpnomelane found?+
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Find stilpnomelane on the map
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