The chemical formula of Quartz is indicated SiO2 or Silicon Dioxide. Quartz is actually a Silicate mineral. It is commonly used as silica for glass, optical lenses, building stones, electrical components, abrasives, ornamental stones and gemstones. It is also used as mineral specimen and it is most often found exhibiting nice and interesting images when viewed under polarizing microscopes used in the field of optical mineralogy. Quartz is actually the most common mineral on the face of the Earth. It can be found in nearly every geological environment and is at least a component of almost every rock type. Quartz is known to e very variable in terms of varieties, colors and forms.
Quartz is usually found showing variable colors as spectrum. However, the most common of all is the clear quartz. It is then followed by the cloudy quartz. Quartz can be also found colored pink, purple, gray or brown to black. Cryptocrystalline varieties of Quartz can be found multicolored. Quartz is usually found exhibiting glassy to vitreous luster as that of crystals, while Cryptocrystalline forms are usually found waxy to dull but can be also vitreous at some times when viewed in reflected light of polarized microscopes for mineralogists. Most crystals of Quartz are found transparent to translucent in appearance. Cryptocrystalline forms can be translucent or opaque. Quartz is known to crystallize in the trigonal system of crystal formation.
The crystal habit of the mineral Quartz is highly variable. The most common habit however is hexagonal prisms terminated with a six sided pyramid. When closely evaluated, it can be noticed that the six sides of the pyramid may dominate causing the pyramid to be or look three sided. Left and right handed crystals are possible and identifiable only if minor trigonal pyramidal faces are present. Druse forms are also common. Massive forms can be just about any type but common forms may actually include globular, botryoidal, stalactitic, crusts of agate such as lining the interior of a geode and many more. Quartz is usually found showing very weak rhombohedral cleavage in three directions that can be seen more clearly exhibited when specimen sample is closely evaluated with the aid of polarizing microscope used in optical mineralogy. Quartz is also usually found showing conchoidal fracture when viewed under petrographic polarizing microscope. The hardness measure of the mineral is usually found 7 or less if in cryptocrystalline form when sample is evaluated suing the Mohs scale method. Quartz is most commonly found leaving a white streak when specimen is rubbed on a white porcelain streak plate. The specific gravity measure of the mineral is 2.65 grams per cubic centimeters or less if in cryptocrystalline form. Quartz can be found showing striations on prism faces run perpendicular to c-axis when specimen sample is closely evaluated under polarizing microscope. Quartz is also known to be piezoelectric with index of refraction found to be 1.55. The best field indicators of Quartz usually include hardness, striations, crystal habit, lack of good cleavage and good conchoidal fracture. Quartz is usually found associated with other interesting minerals including tourmalines, topaz, microcline, elbaite, calcite, rutile, gold, wolframite, zeolites, fluorite, beryl, spodumene and hematite. Quartz notably occurs at several localities including Russia, Brazil, Mexico, Germany, Africa and many areas in USA.
