Chal´cedony (), a precious stone, forming a variety of amorphous quartz. It is harder than flint (specific gravity 2.04), commonly semi-transparent, and is generally of one uniform color throughout, usually a light brown and often nearly white; but other shades of color are not infrequent, such as grey, yellow, green, and blue. Chalcedony occurs in irregular masses, commonly forming grotesque cavities, in trap rocks and even granite. It is found in most parts of the world; and in the East is employed in the fabrication of cups and plates, and articles of taste, which are wrought with great skill and labor, and treasured among precious things. In Europe it is made into snuff-boxes, buttons, knife-handles, and other minor articles.