瑪瑙是玉髓類礦物的一種，經常是混有蛋白石和隱晶質石英的紋帶狀塊體，硬度7-7.5度，比重2.65，色彩相當有層次。有半透明或不透明的。常用做飾物或玩賞用。古代陪葬物中常可見到成串的瑪瑙球。瑪瑙具有各種顏色的環帶條紋，質地很象水晶，細膩而沒有雜質，有玻璃的光澤，呈現透明或半透明的多層狀，各層互相重疊，有波紋、同心、斑駁、層狀等多種花紋。Agate is a type of chalcedony mineral, often a striate mass mixed with opal and cryptocrystalline quartz, with a hardness of 7-7.5 degrees, a specific weight of 2.65, and a fairly layered color. Translucent or opaque. It is often used for making decorations or toys. Strings of agate balls are often seen in ancient burial objects. Agate has all sorts of color band stripes, like crystal texture, exquisite and without impurities, have a glass of luster, rendering transparent or translucent layers, each layer overlapping, corrugated, concentric, mottled, layered and other decorative pattern.