Links to Smoky Quartz Mineral Information Topics On This Page:
Smoky Quartz items in our VIRTUAL GALLERY
Smoky Quartz Physical Properties
Smoky Quartz Background Info
Smoky Quartz Occurance Info and Diagnostic Features
Smoky Quartz Historical Info and Uses
Smoky Quartz Metaphysical Information
Smoky Quartz is a macrocrystalline variety of the mineral Quartz (SiO2). Quartz is the most abundant single mineral on earth. It makes up about 12% of the earth's crust, occurring in a wide variety of igneous, metamorphic and sedimentary rocks.
Quartz varieties are commonly separated into two groups based on the size of the individual grains or crystals; macrocrystalline quartz in which individual crystals are distinguishable with the naked eye, and cryptocrystalline quartz in which the individual crystals are too small to be easily distinguishable under the light microscope.
Some of the macrocrystalline quartz varieties are: Amethyst, Ametrine, Cats-eye Quartz, Citrine, Phantom Quartz, Rock Crystal, Rose Quartz, Rutilated Quartz and Smoky Quartz.
Blue Aventurine Quartz and Green Aventurine Quartz are actually quartzites (a rock, not a mineral) composed essentially of interlocking macrocrystalline quartz grains with disseminated grains of other color imparting minerals.
The cryptocrystalline varieties of quartz may be separated into two types;
fibrous and microgranular. Chalcedony is the general term
applied to the fibrous cryptocrystalline varieties.
Agate is an example of a fibrous cryptocystalline
banded chalcedony variety of quartz. Carnelian, Chrysoprase and bloodstone
are other chalcedony varieties.
Chert is the general term applied to the granular cryptocrystalline varieties of quartz, of which flint and Jasper are examples.
Return to the Index of Smoky Quartz Mineral Information Topics
Smoky quartz is transparent quartz that is brown, gray or black. It commonly occurs in quartz veins where it crytallizes inside rock cavities known as vugs. It also is common in vugs or pockets in pegmatite dikes. Smoky quartz can occur as secondary quartz crystals on cryptocrystalline quartz in cavities and vugs forming geodes.
The characteristic color of smoky quartz occurs in nature when rock
crystal quartz is exposed to natural radiation
from radioactive elements or adjacent radioactive rocks over long periods
of time. The process by which this occurs is not completely understood,
although it is known that exposure of transparent quartz to radiation
can alter the oxidation states of impurities in the quartz
structure resulting in the characteristic colors of smoky quartz. Subsequent
heating reverses this process.
Rock crystal specimens are synthetically irradiated to smoky quartz for commercial purposes.
Smoky quartz often has minute cavity inclusions containing carbon dioxide or water. If there is a sufficient number of these minute fluid inclusions then the quartz becomes opaque and is called milky quartz. Most smoky quartz forms on a matrix of milky quartz and crystals of smoky quartz often grade into milky quartz towards their base. Smoky quartz often has cavities containing both liguid and gas phases known as a two-phase inclusions or quartz enhydros. In rare cases, two-phase inclusions in quartz can be visible to the unaided eye and may show actual movement of the gas phase within the liquid phase.
Smoky quartz sometimes forms with an etched pattern of lines, depressions and raised terminations. If these etched terminations are accompanied by plainly visible internal cavities arranged in geometric patterns related to the quartz crystal structure, the form is referred to as skeletal or 'elestial' quartz. The internal cavities of skeletal quartz often contain clay minerals of varied colors, sometimes accompanied by carbon dioxide or water. These cavities can have a layered or ribbed aspect and are sometimes so pronounced as to make the crystal almost hollow, giving rise to the term skeletal quartz. Occaisionally these cavities contain both liguid and gas phases together known as two-phase inclusions. In rare cases, these two-phase inclusions in skeletal quartz may show actual movement of the gas phase within the liquid phase (popularly known as elestial smoky quartz 'enhydros').
Many different minerals can form as inclusions within smoky quartz. Some of the more important varieties of included quartz for gem use are rutilated quartz and tourmalinated quartz. Some other common mineral inclusions in smoky quartz are chlorite, goethite and hematite.
Phantom quartz shapes are sometimes present in the interior of smoky quartz crystals, outlining an earlier stage of the crystal's formation. The phantom shapes within these phantom quartz crystals are usually composed of other minerals such as chlorite or of other varieties of quartz such as milky quartz, colorless rock crystal, or smoky quartz of lighter or darker shades which form on most or all of the surfaces of the quartz crystal at a particular point in time during its growth, after which the quartz crystal resumes its crystallization enclosing the phantom crystal outline within itself.
Smoky quartz is recognized by its crystal habit, transparency, hardness, glassy luster, color, conchoidal fracture, occurance and general lack of cleavage.
Return to the Index of Smoky Quartz Mineral Information Topics
Pliny wrote nearly 2000 years ago that quartz crystals formed from ice exposed to intense cold for long periods of time in dark clefts and caverns in the mountains. This general belief was popular in diverse cultures until the eighteenth century, when modern geology began to develope in Europe.
Smoky quartz has been used as gemstones and other ornamental and religous objects for thousands of years. The very dark brown to black smoky quartz is sometimes called morion. Faceted brown smoky quartz has been called smoky topaz, and also is known as Cairngorm, named after an old locality in the Cairngorm Mountains in the Scottish highlands.
The name quartz comes from the Saxon word querklufterz which meant cross vein ore.
The astrological signs of smoky quartz are Capricorn and Sagitarius.
Wearing smoky quartz jewelry is said to alleviate stress and transform fear, anger and other negative emotions into positive energies, thus having a comforting and calming effect. It is also said to provide clarity of thought, improve intuition and enhance survival instincts, and to stimulate higher awareness in meditative states.
Smoky quartz is said to increase fertility, to help remove toxins from the body, and to aid the proper functioning of the kidneys, adrenals, pancreas and sex organs.
For more in-depth metaphysical information, see our Metaphysical Books section.
This is the end of our Smoky Quartz Mineral Information page.
See also our natural quartz crystals, and our natural quartz crystal balls.
To see smoky quartz photos, just select any linked image below.
To see photos of another mineral variety, select anylink in our Mineral Inventory & Factsheet Index.