Translucent, semiprecious variety of the silica mineral chalcedony that owes its red to reddish brown color to the incorporation of small amounts of iron oxide.

• 二氧化矽矿物玉髓的半透明、次宝石变种。由于存在分散的胶体赤铁矿（氧化铁）故呈红色到红褐色或肉红色。