Brown Quartz and Smoky Quartz

Brown Quartz and Smoky Quartz are the light, dark, or greyish (smoky quartz) brown varieties of the quartz family. The black variety is called morion. Brown quartz crystals are hexagonal prisms with pyramidal ends. The inclusions of mineral rutile may be present inside the crystal. Brown quartz has been confused with axinite, andalusite, idocrase, and brown tourmaline. Similar to other varieties of quartz, smoky quartz may be polished and fashioned in many ways.

Intaglio seals were popular with the Ancient Romans. It is made by carving the smoky quartz and setting it in a polished oval of obsidian, a natural volcanic glass.

Smoky quartz

Brown or smoky quartz from the Cairngorm Mountains of Scotland is cairngorm. When irradiated, colorless quartz may change color to greyish brown. It suggests that brown quartz may have been formed by natural radiation within the ground. It is common to find waterworn cairngorm pebbles. Much of the smoky quartz on the market is irradiated rock crystal.

Occurrence

Brown quartz (smoky quartz) crystal weighing as much as 300kg (650lb) have been found in Brazil. Other localities include Spain, Australia, Colorado (USA), the Swiss Alps, and Madagascar.

Brown Quartz and Smoky Quartz Properties

• Specific Gravity: 2.65
• Refractive Index: 1.54-1.55
• Birefringence (DR): 0.009
• Luster: Vitreous
• Crystal Structure: Trigonal
• Composition: Silicon dioxide
• Hardness: 7

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