Magnesium Iron Silicate
(Mg,Fe)2SiO4
Chemical name
Magnesium Iron Silicate
Mineral name
Olivine
Chemical formula
(Mg,Fe)2SiO4
Crystal system
orthorhombic
Crystal Class
orthorhombic-dipyramidal (2/m 2/m 2/m)
Space Group
Pbnm
Unit cell
a [Å]:6.01
b [Å]:4.78
c [Å]:10.30
Formula units
Z=4
Frequent crystal surfaces
{110}, {120} combinated with {021}, {101}, {111} and {010}
Mohs hardness
6.5 - 7
Density [g/cm3]
3.2 - 4.5
Cleavage
good on {001}, clear on {010}
Fracture / Tenacity
brittle to conchoidal
Color
yellow to yellow-green
Streak
white
Transparency
transparent to translucent
Optical character
biaxial (+)
Refractive Index
nα=~1.640; nβ=~1.660; nΥ=~1.680
Birefringence δ
0.040