Chalcedony Facts
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Chalcedony Physical Properties
| Chemical Composition | The chemical composition is Silicon dioxide and the chemical formula is SiO2. |
| Colours | Varied colours. |
| Hardness | Varies between 6.5 – 7 Mohs. |
| Refractive Index | 1.543 – 1.554 |
| Specific Gravity | 2.65 – 2.67 |
| Luster | Waxy to dull. |
| Solid State | Opaque to translucent. Few varieties can be transparent too. |
| Crystal System | Tetrahedral crystal system. |
| Cleavage | None |
| Heat Sensitive | No |
| Fractures | Conchoidal |
| Bi-refringence | 0.009 |
| Pleochroism | None |
| Source | Worldwide occurrence. Main producers are United States and Brazil. |
| Enhancement | Not enhanced. |
| Precautions | Only 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.