Stilpnomelane

A variety of Minerals

What is Stilpnomelane?

Stilpnomelane is a phyllosilicate mineral. It has the formula K(Fe,Mg,Fe)8(Si,Al)12(O,OH)27·n(H2O). Stilpnomelane occurs associated with banded iron formations. It is a metamorphic mineral associated with the blueschist and greenschist facies. It was first described in 1827 for an occurrence in Moravia in the Czech Republic. The name is derived from the Greek stilpnos for shining, and melanos for black.

Market Value Factors

Pricing varies for every rock and mineral, so use these universal factors to gauge Stilpnomelane before comparing listings or appraisals.

Size & Weight

Larger, intact specimens usually command higher prices.

Rarity & Demand

Scarce material or popular varieties sell at a premium.

Condition & Finish

Chips, repairs, and heavy wear lower value; clean prep helps.

Treatment & Provenance

Untreated specimens with documented locality are prized.

Applies to all rocks & minerals.

Stilpnomelane Localities Map

See where Stilpnomelane is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

Map preview

North ZoneCentral RidgeSouth Basin

Quick Facts

Physical Properties

Color: Red, brown, black, dark green, dark reddish brown, golden brown
Hardness (Mohs): 3 - 4
Density: 2.667 g/cm³
Streak: White, grey

Chemical Properties

Chemical Formula: (K,Ca,Na)(Fe,Mg,Al)₈(Si,Al)₁₂(O,OH)₃₆ · nH₂O The ratio of ferric vs. ferrous iron varies greatly. An ideal end-member "ferrostilpnomelane" can be represented by K₅Fe⁴⁸²⁺(Si₆₃Al₉)O₁₆₅(OH)₄₈.12H₂O. An ideal end-member "ferristilpnomelane" (which is thought to result from oxidation after primary crystallization) can be represented by K₅Fe⁴⁸³⁺(Si₆₃Al₉)O₂₁₆.36H₂O. Note that neither end-member composition has been reported yet.
Elements: Al, Ca, Fe, H, K, Mg, Na, O, Si

Also Known As

StilpnomelaneMinguetite

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Stilpnomelane FAQs

How do I identify Stilpnomelane?

Stilpnomelane can be identified by its hardness of 3 - 4 on the Mohs scale, Red color. Look for these key characteristics when examining specimens.

What color is Stilpnomelane?

Stilpnomelane typically appears in Red, brown, black, dark green, dark reddish brown, golden brown. Color can vary depending on impurities and formation conditions.

How hard is Stilpnomelane?

Stilpnomelane has a hardness of 3 - 4 on the Mohs scale. This makes it a soft mineral that can be scratched easily.