Astrophyllite
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NameAstrophyllite
Chemical Formula(K,Na)₃(Fe,Mn)₇Ti₂Si₈O₂₄(O,OH)₇
Mohs Hardness3
Crystal Systemtriclinic
Streak Coloryellowish-brown
Cleavageperfect on {001}
Fractureuneven
Specific Gravity3.3
Colorsgolden-yellow, bronze-yellow, reddish-brown, dark brown
Transparencyopaque
Type LocalityKhibiny Massif, Kola Peninsula, Murmanskaja Oblast', Northern Region
Mineral Groupsilicates
Usescollector, lapidary
Associated Mineralsfeldspar, nepheline, aegirine, arfvedsonite, eudialyte
Rarityuncommon
Description
This specimen features radiating, bladed crystals of astrophyllite, displaying a characteristic golden-brown to bronze-yellow color and a distinct submetallic luster, embedded within a lighter matrix.
Geological Context
Astrophyllite typically forms in nepheline syenites and other alkaline igneous rocks, as well as in pegmatites and metasomatized rocks, often associated with rare earth element deposits.
