Euclase is a rare beryllium aluminum silicate known for its brilliant blue or colorless, highly lustrous crystals. Collectors specifically look for its distinct, chisel-like crystal terminations and its propensity to cleave along one plane, which makes it challenging for lapidary work.
Is this euclase?
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 euclase with a known reference. Euclase sits at Mohs 7.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, somewhat pearly on cleavages.
- 4Match the color rangeCompare against the expected color range: colorless, blue, white, light blue, light green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, prismatic, striated.
Often confused with
Euclase vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside euclase
Minerals reported to co-occur with euclase. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BeAlSiO₄(OH)
- Mohs hardness
- 7.5
- Density
- 2.99-3.10 g/cm³
- Streak
- White
- Luster
- Vitreous, somewhat pearly on cleavages
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive, prismatic, striated
- Cleavage
- Perfect on {010}, imperfect on {110} and {001}
- Rarity
- Rare
- Uses
- Gemstone, Collector
- Host rock
- The product of decomposition of beryl in pegmatites, and in low-temperature alpine veins
Where rockhounds find euclase
Classic worldwide localities
- Sanarka River, Orenburg district, and the Kamenka River, Southern Ural Mountains, Russia
- Epprechtstein, Bavaria, Germany
- Muiâne pegmatite, Alto Ligonha district, Mozambique
- Found near Mikese Station, Morogoro district, Tanzania
- Karoi, Miami district, Zimbabwe
- Minas Gerais, around Villa Rica, Boa Vista, Santa do Encoberto, Dom Bosco, Ouro Prêto, Brazil
Field-hunting tip
Where it forms: The product of decomposition of beryl in pegmatites, and in low-temperature alpine veins. If you start seeing feldspar, quartz, topaz in float, you are in the right ground. Typical habit: massive, prismatic, striated. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify euclase?+
Where is euclase found?+
Is euclase safe to handle?+
What rocks look like euclase?+
What minerals are found with euclase?+
What kind of rock does euclase form in?+
What is euclase used for?+
Find euclase on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
