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.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Siderophyllite 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.
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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Siderophyllite FAQs
How do I identify Siderophyllite?
Siderophyllite can be identified by its hardness of 2.5 on the Mohs scale, Dark green color. Look for these key characteristics when examining specimens.
What color is Siderophyllite?
Siderophyllite typically appears in Dark green, brown, black. Color can vary depending on impurities and formation conditions.
How hard is Siderophyllite?
Siderophyllite has a hardness of 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
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