Smoky (Smokey) Quartz
Smoky (Smokey) Quartz is a very common, coarse-grained variety of the silica mineral Quartz that ranges in color from nearly black through smoky brown. No distinct boundary exists between smoky and colorless Quartz. Its abundance causes it to be worth considerably less than either Amethyst or Citrine. Heating bleaches the stone, the color sometimes passing through yellow. These yellow pieces are often sold as Citrine. Crystals of the mineral frequently contain inclusions of gas (carbon dioxide), liquid (often both water and liquid carbon dioxide), or solids (rutile). Smoky Quartz from Mount Cairngorm , Scotland , is known as cairngorm and is a favourite ornamental stone in Scotland , where it is worn in brooches with Highland costume. Its properties are those of other Quartz gemstones. Today, the vast majority of smoky quartz is mined in Brazil , but it is found in most of the major gemstone producing nations.
Smoky (Smokey) Quartz is a popular variety of Quartz, which is sometimes used for unusual faceted cuts. It has an unusual color for a gemstone and is easily recognized and is well known by the general public. Only a few other brown or black minerals are ever cut for gemstones such as the Smoky Quartz, the very rare black beryl or the brown corundum. Smoky Quartz is also popular as an ornamental stone and is carved into spheres, pyramids, obilisks, eggs, figurines and ornate statues.
Smoky quartz, a variety itself of quartz, has a few varieties of its own:
- Cairngorm is a variety that comes from the Cairngorm Mountains in Scotland.
- Morion is a very dark black opaque variety of Smoky Quartz.
- Coon tail Quartz is a Smoky Quartz with an alternating black and gray banding.
The color of Smokey Quartz is variable from brown to black and sometimes smoky gray colored specimens are included as Smoky Quartz. The cause of the color of Smoky Quartz is in question but it is almost certainly related to the amount of exposure to radiation that the stone has undergone. Natural Smoky Quartz gemstones often occurre in granitic rocks which have a small but persistant amount of radioactivity. Most Smokey Quartz gemstones that make their way to rock shops and to some gem cutters have been artificially irradiated to produce a dark black color.
Natural Smoky Quartz comes from many sources around the world. A few of the more noteworthy locations include Brazil, the worlds largest supplier; Pikes Peak area of Colorado, USA, where it is associated with green Amazonite and the Swiss Alps, which has produced many tons of fine specimens.
Smoky Quartz is quite often sold in the trade as Smoky (Smokey) Topaz. 99% of the time a gemstone offered as Smoky Topaz is actually this variety of Quartz. Since Topaz is a separate mineral, this type of name can be confusing and should be clearly disclosed as to which gemstone is actually being presented, since Topaz also occurs in a brown color.