Euclase Mineral Guide

Euclase

Curated by Maggie Liu · Updated: July 15, 2026

Crystal system · Monoclinic

Euclase is a mineral recognized among collectors for its crystal form and distribution, with several world-class Chinese localities.

Euclase specimen — Photo: Robert M. Lavinsky · CC BY-SA 3.0 via Wikimedia Commons

About Euclaseextended article

Market availability: Rare

Sought after; limited supply. Major shows and specialist dealers only.

Geological setting

PegmatiteAlpine cleft

Crystal system
Monoclinic

Euclase is a beryllium-aluminum nesosilicate prized for its rare gem-grade aquamarine-blue crystals. The name (Greek “eu-klasis”, easy to break) reflects its perfect prismatic cleavage that makes faceted euclase a connoisseur’s gem rarely seen outside specialist collections.

Occurrence

Premier sources: Ouro Preto and Capão (Minas Gerais, Brazil) for sky-blue gem crystals; Last Hope Mine (Zimbabwe) for the deepest blue color; Russia and Pakistan for additional material.

Identification

Sky-blue color + perfect lateral cleavage + monoclinic prismatic crystals + association with quartz/beryl in pegmatites or alpine clefts. Distinguish from aquamarine (beryl, hexagonal, no perfect cleavage).

Collector Notes

Brazilian sky-blue euclase from Ouro Preto is among the most coveted of all gem rarities. The cleavage makes faceting tricky — euclase gems are connoisseur targets.

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Published: May 6, 2026 · Last reviewed: May 6, 2026
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About Euclase

Euclase belongs to the mineral class. Its crystal form varies within the species and holds a steady position among mineral species. Its combination of structural character and global distribution make it a recognized species in both systematic and aesthetic collections.

Collector context

Classic Chinese localities

Documented Chinese occurrences are recorded at Xianghualing Sn-polymetallic ore field, Xihuashan ore field and Yaogangxian W-Sn ore field, among others.

Why collectors care

Euclase is a frequently-sought species in serious collections because its habit is recognizable, its color often strong, and its best examples unmistakable even at a distance. Chinese material has driven much of the recent visual shift in the species — sharper crystals, deeper colors, cleaner matrix.

What affects value

Value in Euclase is assessed, in typical order of weight, against: (1) locality provenance; (2) size relative to the species norm; (3) crystal form and termination sharpness; (4) color saturation and zoning; (5) transparency and internal clarity; (6) matrix quality and aesthetic balance; (7) condition (absence of damage, chips, or repair). Cleaning quality and verified locality documentation act as multipliers across the above.

Frequently asked questions

What is Euclase?

Euclase crystallises in the Monoclinic system. Euclase is a mineral recognized among collectors for its crystal form and distribution, with several world-class Chinese localities.

What crystal system does Euclase belong to?

Euclase crystallises in the Monoclinic crystal system.

Is Euclase rare?

As a collector mineral, Euclase is generally considered rare.

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