Physical, Chemical and Structural Properties of Quartz, for Identification and Classification in Geology, Mineralogy, Crystallography and Gemology studies for professionals and Rock Collectors

This site contains information on the Physical Properties and Chemical Composition of Minerals, gemstones, crystals, precious metals, and sedimentary, igneous and metamorphic rocks for crystallography, geology, identification of minerals, Jewelry and mineralogy. This includes cleavage, description of crystal formations, crystal structure, hardness, specific gravity, Mohs’ Scale, crystal features and crystal habits for identification and classification purposes.

Quartz is one of the most common compounds in the Earth’s Crust and one of its most useful. Throughout history, it had gemstone, spiritual, ornamental and collecting uses. In modern times, it has moved from the ground right into your house. You can now find Quartz in many everyday items, including sandpaper and other abrasives, soap, and ceramics. But it is also in high-tech items such as radios, TVs, Clocks, watches and computers. Its piezo-electric properties make it highly useful in modern technology, because in electric tests, it was shown to produce regular electric pulses and field changes that inventors could predict. As the technology for creating synthetic Quartz evolved, they began using it to regulate the frequency of electronic devices. It was the first crystal used in radio wave transceivers, is used in watches and timepieces, and was essential in the development of computers. 

The information below refers to the Scientific properties of Clear Quartz, also known as Rock Crystal. Smoky, Rose and Rutilated Quartz properties are covered briefly under “Varieties.”

Chemical Properties
Clear Quartz is pure, or nearly pure Silicon Dioxide (SiO2), made of Silicon and Oxygen, the Earth’s most common elements. Any impurities are generally trace elements of Aluminum, Lithium, Potassium or Sodium. Quartz has also been found in meteorites and moon rooks.

Quartz in other Minerals
Nearly every type sedimentary, igneous and metamorphic rock contains quartz in one form or another and of varying concentrations. It is essential in the formation of most igneous rocks, including Granites, granodiorites, rhyolites. The weathering of igneous rocks removes most other minerals but Quartz grains resist the erosion process, collect together and when compressed make Sedimentary formations. When Sedimentary rocks containing Quartz enter a Metamorphic process, the Quartz grain sizes change greatly. Quartz crystals, of many forms, also make up the lining found in Geodes.

Crystal System
The primary Microcrystalline crystal classification of Quartz is Trigonal, containing four axes, three of which intersect to form a plane intersected by the fourth. Based on impurities or disruptions of the formation process, samples can contain encrustations and phantom crystals, can form hexagonal prisms twinnings, or double terminations. They can show up in Geodes in any formation, as Macrocrystalline Chalcedonies, or massive structures. One other mineral shares isostructural crystal formation with Quartz; it is a very rare Phosphate called Berlinite (A1PO4).

Physical Properties of Clear Quartz
Hardness: 7.0 on Moh's Scale
Index of refraction: 1.544-1.553
Birefringence: 0.009
Streak: White
Spec. Grav.: 2.5 - 2.7 
Crystal: Hexagonal (prisms, pyramidal) 
Fracture: Conchoidal
Cleavage : none
Tenacity: Brittle
In Group: Silicates; Tectosiliates; Silica Group: or as an oxide by a few references 
Other Names: Silica (describes Quartz, Chalcedony, and Opal)
Alpha Quartz or High Quartz (describes Quartz stable at normal room conditions
Environment : develops in a wide variety of environments, igneous, metamorphic, hydrothermal
Transparency: Transparent to opaque
Luster: Most specimens have a vitreous luster; Some yellow or brown are resinous; Earthy specimens are dull; Very rare varieties have an adamantine luster
Other Marks for identification purposes: Many specimens fluoresce;  All specimens are triboluminescent and piezoelectric 
Striking Features: Hardness, crystal forms, striations on crystal faces, and frequent appearance of  conchoidal fractures on crystal faces.
Complex Tests: Dissolves in hydrofluoric acid
Distinguishing from Similar Minerals: Beryl is harder (7½ - 8), without the horizontal striations of Quartz; Feldspar is a softer stone (6), with perfect cleavage; Calcite is very soft (3)
Typical Cutting Styles---Faceted, cabochons 

Varieties of Quartz
Other than Clear Quartz, Quartz occurs as Amethyst, Aventurine, Citrine, Carnelian, Herkimer Diamonds, Jasper, Onyx, Rose Quartz, Rutilated Quartz, Smoky Quartz and Tourmalinated Quartz. Rose, Rutilated and Smoky Quartz will be covered here. The properties of Amethyst, Aventurine, Citrine Carnelian Jasper and Onyx are covered elsewhere in JewelrySupplier.com. Herkimer Diamonds are Quartz crystals with double terminations and Tourmalinated Quartz contains hairs of Tourmaline crystals, but both are minor Quartz family members. 

Rose Quartz-Rose Quartz’ pink to rosy-red color, unique among minerals and caused by impurities of Iron and Titanium, makes it highly desirable as a gem and ornamental stone. It occurs primarily as a cabochon in jewelry or as a carving. It occurs most often as massive formations but deposits of crystals have been found in modern times. Rutilations in Rose Quartz can create a highly attractive star effect. It is also more often translucent than transparent.
Index of refraction: 1.544-1.553
Birefringence: 0.009
Hardness: 7
Cleavage: none
Crystal system: trigonal

Rutilated Quartz-Rutilated is a variety of Quartz Crystal containing impurities of Titanium Dioxide, that form needles within the Quartz. Some have called it Venus’ Hair Stone. This stone is treasured for the beauty of its Ritulations and is used as a cabochon in jewelry.
Index of refraction: 1.544-1.553
Birefringence: 0.009
Hardness: 7
Cleavage: none
Crystal system:trigonal 

Smoky Quartz-Its colors range from tan, brown to light gray and make it rare in the mineral world, where only a few others take on brown or black color. It occurs as Cairngorm, from the mountains in Scotland, Morion, one of the dark black varieties, and Coon Tail Quartz, which forms bands of gray and black. Scientist debate the source of the color, but some believe it comes from exposure to radiation. Others attribute the color to traces of Aluminum. It is sometimes misleadingly sold as Smoky Topaz. If the sample contains ritulations, it is called Smoky Sagenite.Index of refraction: 1.544-1.553
Birefringence: 0.009
Hardness: 7
Cleavage: none
Crystal system:trigonal  

Quartz
Links

Quartz Main Page

Quartz Geography
Locations of Deposits and Production Information

Quartz Healing
New Age, Spiritualist and Religious uses for Mental and Physical Healing

Quartz History
Role in World and National History

Quartz Mythology
New and Ancient Myths and Legends

Quartz Properties
Physical and Chemical Distinctions for Identification

Quartz Sleep/Dreams
Superstitions About Dreaming and Sleep

Quartz Spirituality
Beliefs about Role in the Spirit World

Quartz Symbolism
Corresponding Birth and Astrological Signs

This site is sponsored by Albuquerque 505 Wholesale Jewelry. Visit their site for Wholesale Merchandise, discounted Silver and Sterling Silver Fashions and designs.

Jewelry Supplier's Everything About Semi-precious Stones site provides a wide range of iJewelrySupplier.com is intended to provide information, use and history of gemstones and semi-precious stones. JewelrySupplier.com neither advocates nor makes any claims regarding the success of using crystals for healing, magical or spiritual ends in place of traditional medical methods. Copyright 1999, JewelrySupplier.com