orthorhombic Nesosilicates
Peridot
Formula (Mg,Fe)2SiO4
Crystal Structure
#! Species: Peridot (Olivine)
#! System: Orthorhombic (mmm)
#! Habit: Short prismatic with lily pad inclusions
orthorhombic[mmm]:{110}@1.0[inclusion:lily_pad] + {010}@0.7 + {021}@0.5
orthorhombic
mmm
{110} {010} {021}
Quick Facts
Hardness
6.5
Specific Gravity
3.27
Refractive Index
1.654
Optical Character
Biaxial +
Physical Properties
- Crystal System
- orthorhombic
- Hardness (Mohs)
- 6.5
- Specific Gravity
- 3.27
- Cleavage
- Poor
- Fracture
- Conchoidal
- Lustre
- Vitreous to oily
Optical Properties
- Refractive Index
- 1.654
- Birefringence
- 0.035-0.038
- Optical Character
- Biaxial +
- Dispersion
- 0.02
- Pleochroism
- weak: Yellow-green / Green / Greenish-yellow (Subtle difference; may be difficult to detect)
Characteristics
Colours
Yellow-greenOlive greenLime greenBrownish-green
Localities
Myanmar (Mogok)Pakistan (Kashmir)China (Changbai)Arizona, USAEgypt (Zabargad)VietnamEthiopia
Common Inclusions
Lily pad inclusions (diagnostic)Chromite crystalsNeedle inclusionsNegative crystalsHealing feathers
Crystal Forms
prismpinacoiddome
Diagnostic Features
Strong doubling visible through table; distinctive yellowish-green; high birefringence (0.036)
Related Minerals
Other minerals in the orthorhombic system
