Chalcedony Facts

Chalcedony Facts

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Chalcedony  Physical Properties

Chemical CompositionThe chemical composition is Silicon dioxide and the chemical formula is SiO2.
ColoursVaried colours.
HardnessVaries between 6.5 – 7 Mohs.
Refractive Index1.543  – 1.554
Specific Gravity2.65 – 2.67
LusterWaxy to dull.
Solid StateOpaque to translucent. Few varieties can be transparent too.
Crystal SystemTetrahedral crystal system.
CleavageNone
Heat SensitiveNo
FracturesConchoidal
Bi-refringence0.009
PleochroismNone
SourceWorldwide occurrence. Main producers are United States and Brazil.
EnhancementNot enhanced.
PrecautionsOnly general gemstone precautions required.

NOTE – These properties are largely for the Chalcedony as a group name. It is common to almost all the varieties. However, few exceptions would always be present.