Smoky or smokey quartz is a brown to black variety of quartz. Like the other quartz gems, it is a crystal of silicon dioxide. The smoky color results from free silicon, formed from the silicon dioxide by natural irradiation.

A very dark brown to black opaque variety is known as morion. Morion is the German, Danish, Spanish and Polish synonym for smoky quartz.

Cairngorm is a variety of smoky quartz crystal found in the Cairngorm Mountains of Scotland. It is smokey yellow-brown color, though some specimens are a grey-brown.

It is used in Scottish jewelry and as a decoration on kilt pins. The largest known cairngorm crystal is a 52 pound specimen.