Judging quality
The blades have a bright metallic-bronze schiller and lie in flat radiating sprays. Golden mica in matrix looks similar but lacks the star arrangement.
Silicate
Astrophyllite
Bronze-gold blades radiating in star-bursts through dark nepheline syenite. The name means star leaf, and a good slab looks like a night sky of gold flares.
Care
Soft with perfect cleavage; the blades flake. Handle gently and avoid ultrasonics.
History & lore
First described from the Norwegian island of Låven in 1854; the Kola material of the twentieth century made it a collector staple.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Astrophyllite
- What is Astrophyllite?
- Bronze-gold blades radiating in star-bursts through dark nepheline syenite. The name means star leaf, and a good slab looks like a night sky of gold flares.
- How hard is Astrophyllite and what is it made of?
- Astrophyllite is a Silicate-family mineral with the composition K2NaFe7Ti2Si8O26(OH)4F. It crystallizes in the triclinic system and rates 3-4 on the Mohs hardness scale. It occurs in bronze, golden, black.
- Where does Astrophyllite come from?
- Notable localities for Astrophyllite include Kola Peninsula, Russia, Greenland, Norway (Låven), Colorado, USA.
- How do you tell good Astrophyllite from filler?
- The blades have a bright metallic-bronze schiller and lie in flat radiating sprays. Golden mica in matrix looks similar but lacks the star arrangement.
- How do you care for Astrophyllite?
- Soft with perfect cleavage; the blades flake. Handle gently and avoid ultrasonics.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.