Chalcedony
What is Chalcedony?
Chalcedony is a form of silica, composed of very fine intergrowths of quartz and moganite. It’s found in various parts of the world including Brazil, Turkey, and the United States. Chalcedony comes in a variety of colors and is often used as a gemstone.
Chalcedony is a versatile gemstone that comes in a range of colors including blue, pink, and green. Its unique appearance and color make it a popular choice for jewelry and decorative items, especially beads and pendants.
| Chemical Classification | Inorganic - Silicate (Chalcedony) |
| Color | Chalcedony comes in a variety of colors, including blue, green, pink, red, and yellow, but it's most commonly found in bluish-white or gray shades. |
| Streak | White |
| Luster | Waxy to vitreous. |
| Transparency | Opaque to translucent. |
| Occurrence | India, Brazil, and Madagascar. |
| Formation | Chalcedony forms in a variety of geological settings, from cavities in volcanic rocks to sedimentary formations. |
| Diaphaneity | Translucent |
| Cleavage | Perfect in one direction |
| Mohs Hardness | 6.5 to 7. |
| Specific Gravity | 2.58-2.64. |
| Diagnostic Properties | Waxy luster, various colors. |
| Chemical Composition | SiO2 |
| Pleochroism | None. |
| Crystal System | Hexagonal (variety of Quartz) |
| Optical Properties | Uniaxial (+) |
| Refractive Index | 1.530 - 1.539 |
| Birefringence | 0.009 |
| 2V angle | Measured: 58° |
| Dispersion | Not notably high. |