mineral

Astrophyllite

Astrophyllite (K2NaFe7Ti2Si8O26(OH)4F)

Hardness: 3-4 on Mohs scale; Color: Bronze, golden-yellow, to brownish-black; Luster: Sub-metallic to pearly; Crystal structure: Triclinic (bladed or stellate aggregates); Cleavage: Perfect in one direction; Specific Gravity: 3.3-3.4

Hardness: 3-4 on Mohs scale
Color: Bronze, golden-yellow, to brownish-black
Luster: Sub-metallic to pearly

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed in rare alkaline igneous rocks like nepheline syenites and pegmatites. It is typically a late-stage hydrothermal mineral. Major deposits are found in the Kola Peninsula (Russia) and Mont Saint-Hilaire (Canada).

Uses & applications

Primarily used as a collector mineral and in jewelry (cabs or wire-wrapped pendants like the one shown). It is not used in mass industry due to its relative rarity and softness.

Geological facts

The name is derived from the Greek words 'astron' (star) and 'phyllon' (leaf), referring to its star-like radiating crystal habits and leaf-like cleavage patterns. It is extremely rare and chemically complex.

Field identification & locations

Identify in the field by the distinct bladed, radiating 'sunburst' or 'needle' patterns of bronze-colored crystals embedded in a lighter matrix (usually white or grey feldspar). Found in very specific alkaline igneous provinces.

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Mineral/Rock

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Metamorphic Rock

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