Astrophyllite
Chemical Formula	(K,Na)3(Fe++,Mn)7Ti2Si8O24(O,OH)7
Species	Silicates
Crystal System	Triclinic
Mohs Scale	3
Specific Gravity	3.2-3.4
Color	Golden brown to yellow; rarely greenish
Streak	Yellowish brown or white
Luster	Greasy, Pearly, Sub-Metallic
Refractive Index	n = 1.680 n = 1.700 n = 1.730
Diaphaneity	Translucent, Opaque
Cleavage	PerfectPerfect on Poor on
Fracture	Irregular/Uneven
Crystal Habit：Tabular to bladed, radiating, stellate aggregates; lamellar masses
Geological Setting：Nepheline syenites and alkali granites.