Siderophyllite
A variety of Minerals

What is Siderophyllite?
Siderophyllite is a rare member of the mica group of silicate minerals with formula KFe2Al(Al2Si2)O10(F,OH)2. The mineral occurs in nepheline syenite pegmatites and granite and aplite greisens. It is associated with microcline and astrophyllite at Pikes Peak, Colorado. It is also found in the alkali pegmatites of Mont Saint-Hilaire, Quebec. It was first described in 1880 for an occurrence near Pikes Peak, Colorado. The name derives from the Greek sideros, iron, and phyllon, leaf, in reference to its iron rich composition and perfect basal cleavage.
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Siderophyllite Localities Map
See where Siderophyllite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Color
- Dark green, brown, black
- Hardness (Mohs)
- 2.5
Chemical Properties
- Chemical Formula
- KFe2+2Al(Al2Si2O10)(OH)2
- Elements
- Al, Fe, H, K, O, Si

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