Sard
What is Sard?
Sard is a variety of chalcedony that is often found in India, Brazil, and Uruguay. It’s primarily used as a gemstone and is popular for its brown to reddish-brown color.
Sard is a unique gemstone that comes in shades of brown to reddish-brown. Its earthy hue and unique appearance make it a popular choice for jewelry and decorative items, especially beads and pendants.
| Chemical Classification | Inorganic - Silicate (Chalcedony) |
| Color | Reddish-brown, varying from deep brown to more translucent reddish hues. |
| Streak | White |
| Luster | Waxy to vitreous. |
| Transparency | Translucent. |
| Occurrence | India, Brazil, and Uruguay. |
| Formation | Typically found in hydrothermal veins and in nodules in volcanic rocks. |
| Diaphaneity | Translucent to opaque |
| Cleavage | Perfect in one direction |
| Mohs Hardness | 6.5 to 7 |
| Specific Gravity | 2.58 - 2.64 |
| Diagnostic Properties | Brownish-red chalcedony. |
| Chemical Composition | SiO2 |
| Pleochroism | Not observed in sard. |
| Crystal System | Hexagonal (variety of Quartz) |
| Optical Properties | Uniaxial (+) |
| Refractive Index | 1.530 - 1.539 |
| Birefringence | 0.009 |
| 2V angle | Not applicable (isometric) |
| Dispersion | Not typically noted for its dispersion. |