Stilpnomelane - (K,Na,Ca)0,6(Mg,Fe2+,Fe3+)6Si8Al(O,OH)27 * 2-4H2O

It was first described in 1827 by Ernst Friedrich Glocke for an occurrence in Moravia in the Czech Republic; the name is derived from the Greek "stilpnos" ("shining"), and "melanos" ("black"), alluding to its appearance. Stilpnomelane is a common mineral in low-grade metagreywackes and blueschist-facies rocks, as well as in metamorphosed iron formations.

Optical Properties

Form: Flaky, radiating and brush-like acicular crystals.
Color: Yellowish, greenish and brownish with strong pleochroism.
Interference colors: From II order to III order, but are masked by the color of the mineral.

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Black platy Radiating stilpnomelane crystals associated with quartz, Blanchard Mountain, Skagit County, Washington, USA. From RRUFF.




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Black platy stilpnomelane crystals associated with quartz, Brunsjo mine, Grythyttan, Vastmanland, Sweden. From RRUFF.




Bibliography



• Bucher, K., & Grapes, R. (2011). Petrogenesis of metamorphic rocks. Springer Science & Business Media.
• Fossen, H. (2016). Structural geology. Cambridge University Press.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Passchier, Cees W., Trouw, Rudolph A. J: Microtectonics (2005).
• Philpotts, A., & Ague, J. (2009). Principles of igneous and metamorphic petrology. Cambridge University Press.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.
• Vernon, R. H. (2018). A practical guide to rock microstructure. Cambridge university press.


Photo
stilpnomelano1154(14).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
stilpnomelano1154(33).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
stilpnomelano1154(34).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
stilpnomelano1154(40).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
stilpnomelano1154(37).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
stilpnomelano1154(38).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
stilpnomelano1154(39).jpg

Flaky, Radiating stilpnomelane crystals (brown) in a blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 2x (Field of view = 7mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 2x (Field of view = 7mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 2x (Field of view = 7mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 2x (Field of view = 7mm)
felsastilpnomelanooo(4).jpg

Flaky, Radiating stilpnomelane crystals in a Blueschist. XPL image, 2x (Field of view = 7mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 10x (Field of view = 2mm)
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Flaky, Radiating stilpnomelane crystals in a Blueschist. XPL image, 10x (Field of view = 2mm)
felsastilpnomelanooo(13).jpg

Flaky, Radiating stilpnomelane crystals in a Blueschist. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. XPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. XPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. XPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. XPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. XPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
laytonville(41).jpg

Radiating stilpnomelane crystals. Laytonville quarry, California. XPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 2x (Field of view = 7mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
laytonville(75).jpg

Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
laytonville(76).jpg

Radiating stilpnomelane crystals. Laytonville quarry, California. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. XPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. XPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
stilpnomelano(tirolo)(8).jpg

Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. XPL image, 10x (Field of view = 2mm)
stilpnomelano(tirolo)(9).jpg

Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
stilpnomelano(tirolo)(10).jpg

Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. XPL image, 10x (Field of view = 2mm)
stilpnomelano(tirolo)(11).jpg

Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
stilpnomelano(tirolo)(12).jpg

Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
stilpnomelano(tirolo)(13).jpg

Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. XPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)
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Radiating stilpnomelane crystals in a quartzite. Tyrol, Italy. PPL image, 10x (Field of view = 2mm)