CHEMISTRY - (K,Na)3(Fe,Mn)7Ti2Si8O24(H2O)7
CRYSTALLOGRAPHY - Triclinic
CRYSTAL GROWTH AND HABITS - Crystals are tabular, bladed or acicular. Groups of crystal may be radiating or stellate. It can also form micaceous groups.
COLOR AND OPTICAL PROPERTIES - Brown to bronzish yellow or golden, also reddish brown; translucent to opaque
HARDNESS - 3. 3.5
SPECIFIC GRAVITY - 3.3 - 3.4
LUSTER - Sub metallic to somewhat pearly
STREAK - Brownish yellow
BREAKABILITY - Astrophyllite has a nearly perfect {001} cleavage and a poor {100} cleavage direction. It is brittle.
OCCURRENCE - Astrophyllite occurs in alkali (basic) igneous rocks like syenite or alkali granites.
ASSOCIATED MINERALS - Aegirine, Albite, Nepheline, Zircon, Biotite, Eudialyte
MINERAL NAME - Named for the Greek words for star and leaf due to its micaceous radiating crystal forms.