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Euclase
Current inventory:  1 gem
 

Chemistry:  BeAlSiO₄(OH)  [Beryllium Aluminum Silicate Hydroxide]

Discovered in 1792;   IMA status: Valid (pre-IMA; Grandfathered).
The name Euclase is from the Greek eu meaning easy and klasis meaning fracture because of its easy cleavage.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/B.01-10

8 : Silicates
B : Nesosubsilicates, with anions unfamiliar to tetraheders, cations of octahedral and tetrahedral orientation [4/6]
01 : Euclase series

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As prismatic crystals commonly morphologically complex, to 12 cm.

Physical Properties

Cleavage:

[010] Perfect, [110] and [001] Imperfect

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

7.5

Density:

2.87 - 3.10 (g/cm³)

Radioactivity:

Not Radioactive

Optical Properties

Color:

Blue, Colorless, White, Light blue, Light green, Light Yellow.

Transparency:

Transparent to Translucent

Luster:

Vitreous (glassy)

Refractive Index:

1.652 - 1.671  Biaxial ( + )

Birefringence:

0.019 - 0.025

Dispersion:

Strong

Pleochroism:

Colorless

Occurances

Geological Setting:

The product of decomposition of beryl in pegmatites, and in low-temperature alpine veins

Type Locality:

Ouro Prêto, Minas Gerais, Southeast Region, Brazil

Year Discovered:

1792

View mineral photos:

Euclase Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Euclase is a very rare gem and is usually found as colorless or in shades of yellow, but is also rarely available in pale green, violet, pale blue and dark blue. The violet and blue material is extremely rare. Euclase is hard enough for jewelry but may be a bit brittle. The hardness (6.5 - 7.5) may be variable within a single crystal. Perfect one direction cleavage makes faceting difficult. Current sources are Brazil, Germany, Mozambique, Russia and Zimbabwe.
 

  
Euclase gems for sale: