smoky quartz (redirected from Cairngormstone)

smoky quartz

Common, coarse-grained variety of quartz that ranges in colour from nearly black through smoky brown. No distinct boundary exists between smoky and colourless quartz. Its abundance causes it to be worth considerably less than either amethyst or citrine. Heating bleaches the stone, the colour sometimes passing through yellow; these yellow pieces are often sold as citrine.

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smoky quartz [′smōk·ē ′kwȯrts]

(mineralogy)

A smoky-yellow, smoky-brown, or brownish-gray, often transparent variety of crystalline quartz containing inclusions of carbon dioxide; may be used as a semiprecious stone. Also known as cairngorm; smokestone.