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)

Sources: South Africa

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