Astrophyllite

astrophyllite

xenotime

kupletskite

djerfisherite

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Formula: K2NaFe2+7Ti2Si8O26(OH)4F
Inosilicate (chain silicate)
Forms a series with kupletskite
Crystal System: Triclinic
Specific gravity: 3.2 to 3.4 measured
Hardness: 3
Streak: Golden
Colour: Bronze-yellow, golden yellow, brown to reddish brown
Common impurities: Nb,Ta,Zr,Al,Mg,Ca
Environments:

Plutonic igneous environments
Pegmatites
Metamorphic environments

Astrophyllite is found in nepheline syenite, syenite pegmatites, alkaline granite and nepheline syenite gneiss. (Dana, HOM). Associated minerals include albite, aegirine, arfvedsonite, nepheline, natrolite, zircon, biotite, leucophanite, eudialyte, catapleiite, djerfisherite, rasvumite, delhayelite and kupletskite (HOM Dana).

Localities

At the the Verkhnee Espe deposit, Kazakhstan, astrophyllite occurs on granite with cámaraite, bafertisite, jinshajiangite, fluoro-leakeite and aegirine (R&M 86-2.165).

At the type locality, Låven, Vestfold, Norway, astrophyllite occurs in a nepheline syenite pegmatite (Mindat).

At the Zagi mountain, Pakistan, astrophyllite is found as inclusions in quartz, microcline, xenotime and bastnäsite, but it has not been observed as free-standing crystals (MinRec 35.3.212).

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