Astrophyllite

inosilicate

djerfisherite

Formula: K2NaFe2+7Ti2Si8O26(OH)4F
Inosilicate (chain silicate)
Forms a series with kupletskite
Specific gravity: 3.2 to 3.4
Hardness: 3
Streak: Golden
Colour: Bronze-yellow, golden yellow, brown to reddish brown
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).

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).

Common impurities: Nb,Ta,Zr,Al,Mg,Ca

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