Quartz is a mineral composed of silicon dioxide and is found in many different varieties. ONYX, AGATE, JASPER, AGAPE, sard, and tigerseye are all varieties of quartz. ONYX is a black or white banded variety of quartz, AGATE is a banded variety with curved lines, JASPER is an opaque variety with a red or yellow hue, AGAPE is a variety of quartz with a milky white color, sard is a variety of quartz with a reddish-brown color, and tigerseye is a variety of quartz with a golden-brown color.