Aegirine is a sodium-rich pyroxene that typically forms long, slender, sharp prismatic crystals that are highly sought after by mineral collectors. It is most frequently identified by its distinct dark green to black color and high luster, often found embedded in alkaline igneous rocks like nepheline syenite. Large, terminated blades from localities like Mont Saint-Hilaire are considered world-class display specimens.
Is this aegirine?
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 aegirine with a known reference. Aegirine sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Aegirine leaves a yellowish-grey streak.
- 3Read the lusterHold the specimen under a strong light. Aegirine typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: green, dark green, black, brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, acicular, radiating aggregates.
Often confused with
Aegirine vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Aegirine leaves yellowish-grey, Augite leaves grayish white.
How to tell apart: Streak differs — Aegirine leaves yellowish-grey, Hornblende leaves grayish-white.
How to tell apart: Streak differs — Aegirine leaves yellowish-grey, Epidote leaves white.
Often found alongside aegirine
Minerals reported to co-occur with aegirine. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaFe³⁺Si₂O₆
- Mohs hardness
- 6
- Density
- 3.5-3.6 g/cm³
- Streak
- Yellowish-grey
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Acicular, Radiating Aggregates
- Cleavage
- Good On {110}
- Rarity
- Common
- Uses
- Collector, Scientific Research
- Host rock
- Alkaline Igneous Rocks, Nepheline Syenites, And Pegmatites
- Typical price
- $10-150 per specimen depending on crystal size and location
Where rockhounds find aegirine
2 mapped spotsClassic worldwide localities
- Mont Saint-Hilaire, Canada
- Kola Peninsula, Russia
- Magnet Cove, USA
- Langesundsfjord, Norway
- Malawi
Field-hunting tip
Look in alkaline igneous rocks, nepheline syenites, and pegmatites country — that is the host setting where aegirine typically forms. If you start seeing microcline, nepheline, eudialyte in float, you are in the right ground. Field specimens usually show a prismatic crystals, acicular, radiating aggregates habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Montana, New York — start trip planning there.
Common questions
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Find aegirine on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
