Euclase
Euclase | |
---|---|
General | |
Category | Nesosilicate |
Formula (repeating unit) | BeAlSiO4(OH) |
IMA symbol | Ecs[1] |
Strunz classification | 9.AE.10 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/a |
Unit cell | a = 4.763, b = 14.29 c = 4.618 [Å]; |
Identification | |
Color | Colorless, white, pale green to deep yellowish green, greenish blue, pale blue to deep blue, and light red |
Crystal habit | Prismatic crystals |
Cleavage | Perfect, perfect on {010}, imperfect on {110} {001} |
Fracture | Conchoidal |
Tenacity | Brittle |
Mohs scale hardness | 7.5 |
Luster | Vitreous |
Streak | White |
Diaphaneity | Transparent, translucent |
Specific gravity | 2.99 - 3.1 |
Optical properties | Biaxial (+) |
Refractive index | n |
Birefringence | |
Pleochroism | May be marked in shades of deep blue |
2V angle | 50° |
Dispersion | r > v |
References | [2][3][4] |
Euclase is a beryllium aluminium hydroxide silicate mineral (BeAlSiO4(OH)). It crystallizes in the monoclinic crystal system and is typically massive to fibrous as well as in slender prismatic crystals. It is related to beryl (Be3Al2Si6O18) and other beryllium minerals. It is a product of the decomposition of beryl in pegmatites.[4]
Euclase crystals are noted for their blue color, ranging from very pale to dark blue. The mineral may also be colorless, white, or light green. Cleavage is perfect, parallel to the clinopinacoid, and this suggested to René Just Haüy the name euclase, from the Greek
References[edit]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Euclase data on Webmineral
- ^ a b Euclase on Mindat.org with location data
- ^ a b Euclase in the Handbook of Mineralogy, Mineral Data Publishers PDF
- ^ Chisholm, Hugh, ed. (1911). . Encyclopædia Britannica (11th ed.). Cambridge University Press.