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.

Hardness

7.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Euclase

Hardness: 7.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this euclase?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch euclase with a known reference. Euclase sits at Mohs 7.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Euclase leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Euclase typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, blue, greenish-blue, white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals with distinct striations, often chisel-shaped.

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: 3.1 g/cm³
Colors: Colorless Blue Greenish-blue White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals with Distinct Striations, Often Chisel-shaped
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Gemstone, Collector
Host rock: Pegmatites and Hydrothermal Veins
Typical price: $100-500 per carat for facet-grade gems, higher for rare crystals

Where rockhounds find euclase

Classic worldwide localities

Minas Gerais, Brazil
Ouro Preto, Brazil
Zagi Mountains, Pakistan
Urals, Russia
Colombian emerald mines

Field-hunting tip

Look in pegmatites and hydrothermal veins country — that is the host setting where euclase typically forms. If you start seeing beryl, topaz, quartz in float, you are in the right ground. Field specimens usually show a prismatic crystals with distinct striations, often chisel-shaped habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify euclase?+

Mohs hardness is 7.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, blue, greenish-blue, white.

Where is euclase found?+

Notable localities include Minas Gerais, Brazil; Ouro Preto, Brazil; Zagi Mountains, Pakistan; Urals, Russia; Colombian emerald mines.

How much is euclase worth?+

Typical asking prices fall in the range of $100-500 per carat for facet-grade gems, higher for rare crystals. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like euclase?+

Euclase is most often confused with Topaz, Blue Beryl, Kyanite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with euclase?+

Euclase commonly co-occurs with Beryl, Topaz, Quartz, Chrysoberyl, Muscovite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does euclase form in?+

Euclase typically forms in pegmatites and hydrothermal veins. Working float back to the host body is the standard way to chase a fresh occurrence.

What is euclase used for?+

Euclase is used in gemstone, collector.

Find euclase on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.