Chalcedony

Chalcedony is a microcrystalline variety of quartz, prized for its silky luster and wide range of colors, from white, gray, and blue to pink, brown, green, or yellow.

It includes many famous varieties, such as agate, carnelian, chrysoprase, onyx, and sardonyx. Found in cavities of volcanic rocks and hydrothermal deposits, chalcedony is highly sought after in mineralogy and jewelry for its natural beauty and the richness of its forms and patterns.