Eucryptite is a relatively rare lithium aluminum silicate mineral found almost exclusively in granitic pegmatites. It is most easily identified in the field by its distinct and bright red to pink fluorescence under short-wave ultraviolet light, which helps distinguish it from quartz.
Is this eucryptite?
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 eucryptite with a known reference. Eucryptite sits at Mohs 6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Eucryptite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Eucryptite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, granular, or rarely as small prismatic crystals.
Often confused with
Eucryptite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside eucryptite
Minerals reported to co-occur with eucryptite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- LiAlSiO₄
- Mohs hardness
- 6.5
- Density
- 2.64-2.67 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive, Granular, Or Rarely as Small Prismatic Crystals
- Cleavage
- Poor in One Direction
- Fluorescence
- Bright Pink to Red Under SW UV
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Granite Pegmatites
- Typical price
- $20-150 for small cabinet specimens
Where rockhounds find eucryptite
2 mapped spotsClassic worldwide localities
- Branchville, Connecticut, USA
- Bikita, Zimbabwe
- Karibib, Namibia
- Tanco Mine, Manitoba, Canada
- Kings Mountain, North Carolina, USA
Field-hunting tip
Look in granite pegmatites country — that is the host setting where eucryptite typically forms. If you start seeing spodumene, albite, quartz in float, you are in the right ground. Field specimens usually show a massive, granular, or rarely as small prismatic crystals habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Mexico — start trip planning there.
Common questions
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Find eucryptite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
