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Gemstone profile and identification guide

Euclase

Euclase is a beryllium aluminum silicate hydroxide mineral occasionally cut as a collector gemstone.

7.5 Mohs Blue, Blue Green Silicate (Euclase)
Euclase

Overview

Euclase is a beryllium aluminum silicate hydroxide mineral occasionally cut as a collector gemstone.

Did you know? The mineral name refers to its easy cleavage, a major consideration in cutting.

Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.

Identification

Name: Euclase

Scientific classification: Silicate (Euclase)

Hardness: 7.5 Mohs

Transparency: transparent

Lustre: vitreous

Crystal system: Monoclinic

Primary colour: Blue

Secondary colour: Blue Green

Colour family: Blues

Monoclinic optics, high birefringence, and excellent cleavage distinguish euclase from many similar-colour gems.

Verification Status

Status: verified-core-fields

Reference priority: GIA, Gem-A, Mindat, International Gem Society

Core identity, locality, and physical-property fields reviewed against standard gemological references.

Values are reported as practical gemological ranges where appropriate.

Physical Properties

Hardness category: hard

Hardness value: 7.5 Mohs

Chemical composition: Beryllium aluminum silicate hydroxide [BeAlSiO4(OH)]

Crystal system: Monoclinic

Common locations: Brazil, Colombia, Zimbabwe, Russia, Austria

Learn more: Gem-A gemstone education resources.

Colour Variations

Usually pale to medium blue or blue-green, with high clarity in facetable pieces.

Optical effects: None specified in the current dataset.

Detailed Gemology

Mineral species: Euclase

Mineral group: Sorosilicate group

Chemical formula: Beryllium aluminum silicate hydroxide [BeAlSiO4(OH)]

Mohs hardness: 7.5

Crystal system: Monoclinic

Lustre: vitreous

Transparency: transparent

Streak: White

Cleavage: Perfect in one direction

Fracture: Conchoidal to uneven

Specific gravity: 3.06-3.10

Refractive index: 1.651-1.670

Optical phenomena: None typically diagnostic

Colour range: Colorless, blue, blue-green, pale green

Common inclusions: Needles, two-phase inclusions, fractures

Geological environment: Pegmatites and hydrothermal beryllium systems

Principal mining regions: Brazil, Colombia, Zimbabwe, Russia, Austria

Important commercial sources: Gem euclase is most commonly associated with Brazilian and Colombian production

Historical significance: A niche collector gemstone due to rarity of facetable material.

Common treatments: Generally untreated.

Synthetic or imitation forms: Glass and synthetic look-alikes can be used as simulants.

Common look-alikes: Aquamarine, topaz, beryl

Jewellery uses: Used mostly as collector faceted gems and mineral specimens.

Care recommendations: Hard but cleavage-prone; avoid impact and pressure in setting and wear.

Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Euclase.

Formation

Forms in pegmatitic and hydrothermal beryllium-bearing environments.

Origin

Gem euclase is most commonly associated with Brazilian and Colombian production

Uses

Best for: Used mostly as collector faceted gems and mineral specimens.

Ideal uses: Collector stones and low-impact jewellery settings.

Euclase FAQ

How can I identify Euclase?

Compare hardness (7.5 Mohs), crystal system (Monoclinic), colour profile, and lustre (vitreous) with your sample. Then cross-check related gemstones listed above.

What colour range does Euclase appear in?

Usually pale to medium blue or blue-green, with high clarity in facetable pieces.

Where is Euclase commonly used?

Collector stones and low-impact jewellery settings.. For maintenance, follow the care guidance in this profile.