Cornelain

Carnelian is a variety of chalcedony, a microcrystalline form of quartz, recognizable by its warm shades of orange, reddish-orange to reddish-brown. Its color is due to the presence of fine particles of iron oxides.

Used since antiquity for making jewelry, seals, and cameos, carnelian is prized for its translucency, silky luster, and luminous color. It forms mainly in cavities of volcanic rocks and sedimentary deposits.