Mineralpedia Details for Euclase
Euclase
Named for the Greek words eu, used as a prefix to mean “fair” or “good,” and, probably, klas, which means “fraction,” likely in reference to the minerals perfect cleavability and cleavage. Euclase is an uncommon mineral that occurs as a decomposition product of beryl in pegmatites, and occurs in low-temperature aplite veins. Many localities, but fine crystals come from localities in Russia, Germany, Mozambique, Tanzania, Zimbabwe, Brazil, and Columbia.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/euclase.pdf
- Formula
- BeAlSiO4(OH)
- Crystal System
- Monoclinic
- Crystal Habit
- Prismatic, Massive - Fibrous, Striated
- Cleavage
- Perfect, None, None
- Luster
- Vitreous (Glassy)
- Color
- blue, colorless, white, light blue, light green
- Streak
- white
- Class
- Monoclinic - Prismatic
- Fracture
- Brittle
- Hardness
- 7.5
- WebMineral
- View Euclase
- Mindat
- View Euclase
Euclase from Calhão creek, Minas Novas, Minas Gerais, Brazil
Well formed, monoclinic prismatic and striated crystals to 9mm on matrix.
Euclase from Conselheiro Pena, Minas Gerais, Brazil
Waterclear, gemmy, prismatic crystals with good terminations.
Euclase from Last Hope mine, Mwami, Karoi dist., Mashonaland West, Zimbabwe
Cluster of deep cerulean-blue Euclase crystals, with colorless zonations, with a large central crystal to 3.5cm that has an excellent complex form with sharp edges and striations. There are also a few smaller crystals with good form to <1cm adjacent to the larger crystal.
The Lost Hope mine produced spectacular Euclase specimens that are prized by collectors and which were also cut into superb blue gemstones. According to the labels accompanying this piece, it was collected in 1977.
Euclase from Capelinha, Minas Gerais, Brazil
Gemmy, waterclear complete Euclase crystal with many faces.
Euclase from Minas Novas, near Malacacheta, Minas Gerais, Brazil
A single, excellent, doubly terminated, colorless Euclase crystal.
