Emerald
From Wikipedia, the free encyclopedia
For other uses, see Emerald (disambiguation).
Emerald
Emerald with host rock
General
Category
Beryl variety
Chemical formula
Beryllium aluminium silicate with chromium, Be3Al2(SiO3)6::Cr
Identification
Color
Green
Crystal habit
Hexagonal Crystals
Crystal system
Hexagonal
Cleavage
Poor Basal Cleavage (Seldom Visible)
Fracture
Conchoidal
Mohs Scale hardness
7.5 - 8.0
Luster
Vitreous
Refractive index
1.576 - 1.582
Pleochroism
Distinct, Blue-Green/Yellow-Green
Streak
White
Specific gravity
2.70 - 2.78
Emeralds are a variety of the mineral beryl (Be3Al2(SiO3)6,) colored green by trace amounts of chromium and sometimes vanadium.[1] Beryl has a hardness of 7.5 - 8 on the 10 point Mohs scale of mineral hardness.[1] Most emeralds are highly included, so their brittleness (resistance to breakage) is classified as generally poor. The word "emerald" comes from Latin smaragdus, via Greek smaragdos, its original source being a Semitic word izmargad or the Sanskrit word, marakata, meaning "emerald" or "green".[2]
