Formula: K2NaFe2+7Ti2Si8O26(OH)4F

Colour: Bronze-yellow, golden yellow, brown to reddish brown.

Lustre: Greasy, Pearly, Sub-Metallic

Hardness: 3

Specific Gravity: 3.2 – 3.4

Crystal System: Triclinic

Member of: Astrophyllite Group > Astrophyllite Supergroup

Name: From the Greek άστρον (“astron”) for “star” and φύλλον (“phyllon”) for “leaf”, in allusion to its habit of starburst-like sprays and micaceous cleavage. It was named by the German chemist, geologist and mineralogist Carl Johan August Theodor Scheerer (1813-1875) in 1854.

Type Locality: Låven, Langesundsfjorden, Larvik – Norway

The mineral was first found in 1844 by the Norwegian mineralogist Paul Christian Weibye  and later described as a brown, micaceous mineral (“brauner Glimmer”) from  Norway . Later Scheerer described it under the name astrophyllite.