Astrophyllite is highly sought by collectors for its stunning, star-shaped radiating crystal clusters known as stellate habits. It is typically found embedded in igneous rocks like nepheline syenite and exhibits a distinct golden-bronze luster that contrasts beautifully with its matrix.
Is this astrophyllite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch astrophyllite with a known reference. Astrophyllite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Astrophyllite leaves a golden-brown streak.
- 3Read the lusterHold the specimen under a strong light. Astrophyllite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: bronze, golden-yellow, brown.
- 5Look at form & habitCrystal system: triclinic. Typical habit: bladed, stellate, radiating sprays.
Often confused with
Astrophyllite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Arfvedsonite is the harder of the two (Mohs 5.5-6 vs. 3); streak differs — Astrophyllite leaves golden-brown, Arfvedsonite leaves grey to bluish-grey; luster reads submetallic on Astrophyllite and vitreous on Arfvedsonite.
How to tell apart: Aegirine is the harder of the two (Mohs 6 vs. 3); streak differs — Astrophyllite leaves golden-brown, Aegirine leaves yellowish-grey; luster reads submetallic on Astrophyllite and vitreous on Aegirine.
How to tell apart: Streak differs — Astrophyllite leaves golden-brown, Biotite leaves white; luster reads submetallic on Astrophyllite and pearly on Biotite.
Often found alongside astrophyllite
Minerals reported to co-occur with astrophyllite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na)₃(Fe,Mn)₇Ti₂Si₈O₂₄(O,OH)₇
- Mohs hardness
- 3
- Density
- 3.3-3.4 g/cm³
- Colors
- Streak
- Golden-brown
- Luster
- Submetallic
- Transparency
- Translucent
- Crystal system
- Triclinic
- Crystal habit
- Bladed, Stellate, Radiating Sprays
- Cleavage
- Perfect Micaceous
- Rarity
- Uncommon
- Uses
- Collector, Lapidary
- Host rock
- Alkaline Igneous Rocks, Pegmatites
- Typical price
- $10-100 for specimens depending on size and star formation quality
Where rockhounds find astrophyllite
Classic worldwide localities
- Kola Peninsula, Russia
- Langesundsfjord, Norway
- El Paso County, Colorado, USA
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Look in alkaline igneous rocks, pegmatites country — that is the host setting where astrophyllite typically forms. If you start seeing aegirine, nepheline, feldspar in float, you are in the right ground. Field specimens usually show a bladed, stellate, radiating sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find astrophyllite on the map
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