Chalcedite
- chalcedony (kal-SED-uh-nee) is microcrystalline or cryptocrystalline quartz; hexagonal (trigonal) crystal system; chemical composition SiO2
- natural material no any treatment
- opaque
- brownish red, orange, pale purple with black stripes
- jasper – general variety term applied to semi translucent to opaque chalcedony of any color or combination of colors, except solid black or specially labeled material, such as bloodstone, onyx, etc.
Identification
- Refractive Index: 1.535-1.539; 1.53 or 1.54 spot reading
- Birefringence: usually not detectable, but may show .004
- Pleochroism: none
- Ultraviolet Fluorescence: generally inert (LW and SW); some may fluoresce a yellowish green (LW and SW)
- Specific Gravity: 2.60 (+.10,-.05)
- Polish Luster: greasy to vitreous
- Fracture: conchoidal; sometimes granular
- Luster: dull to waxy
- Cleavage: none
- Hardness: 6 ½ to 7
- Toughness: good
Birthstone Designation(s)
- jasper – 10:00 pm
Sources: South Africa
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