Description

Tiger Iron

• Tiger’s-eye is a variety of the mineral quartz in which the quartz has replaced crocidolite (a form of asbestos) without disturbing the original fibrous structure of the crocidolite; hexagonal (trigonal) crystal system; chemical composition SiO2 
• opaque
• brown color with grey, silver band of hematite.

Identification

• Optic Character: AGG, if not opaque; DR reaction possible in cat’s-eye Refractive Index: 1.544-1.553 
• Birefringence: .009 (often not detectable) 
• Pleochroism: none 
• Ultraviolet Fluorescence: inert 
• Absorption Spectra: not diagnostic 
• Cause of Color: generally iron oxide 
• Specific Gravity: 2.64 to 2.71 
• Polish Luster: vitreous 
• Fracture: splintery to conchoidal (in cat’s-eye)
  Luster: vitreous to silky
• Cleavage: none 
• Identifying Characteristics: fibrous structure (causes the chatoyancy); the wavy fibrous structure of tiger’s-eye and hawk’s-eye is usually distinctive. 
• Crystal Habit: massive
• Hardness: 7 
• Toughness: good 

Stone information is reference from

Gem Reference Guide, Published by GIA. ISBN 0-87311-019-6

Gemstones of the World, Published by Sterling Publishing Co., Inc NY, ISBN 1-4027-4016-6

Encyclopedia of GEMSTONE, Published by ISHINSHA CO., LTD. ISBN 978-986-251-831-1