The Mineral Quartz

Quartz is only second to feldspar as a mineral on the continental crust of the earth. It consists of a Silicon-Oxygen Tetrahydra  with a continuous framework (SiO2).It is interesting to note that the two tetrahydra share the Oxygen to offer a formula of SiO2 overall. Quartz comes in various forms. Several of them considered as gemstones of the semi precious variety. From ages, quartz has contributed its mite as an important gemstone in Hardstone carvings and in the manufacture of Jewelry in the Middle East and Europe.

Chemical Formula  
SiO2

Derivation of Name  
"quartz," as a word,   is a derivative of the German word "Quartz," earlier known as "twarc"that owes its allegiance to  possibly the Slavic ”tvrdý” for "hard " or the Polish word twardy for "hard".

Occurrence
Quartz is the most widespread mineral on our planet.    Its abundant quantities are available all over the world. It gets formed at any temperature and is plentiful in igneous, sedimentary and metamorphic rocks.  It offers high resistance to chemical as well mechanical weathering.

Gemology
Quartz is a superb gemstone. It is tough, long-lasting and generally accepts shining polish. Popular forms of quartz, mostly exploited as gems are: Amethyst, Rose Quartz, Citrine and Aventurine. Jasper and  Agate are also forms of quartz having a microcrystalline structure.

Source 
Prominent locations of Amethyst include: Brazil, Uruguay, Russia, Mexico, Thunder Bay region of Canada and certain areas of the US. Smoky quartz is found in Brazil, Colorado, Swiss Alps, Scotland and many other places. Rose quartz is widespread, though Brazil accounts for big quantities.

Mineralogy  
It is undoubtedly the most widespread mineral on earth. It is created in almost any geological setting and forms some component of nearly all kinds of rocks. It has frequently been the major mineral, over 98%. Also, it comes in maximum varieties of forms and colors.

Color
Color varies with the spectrum, though the most usual color is clear quartz. Next is milky or white color, followed by pink or Rose Quartz, Purple or Amethyst, gray, and brown to black, called Smoky Quartz. Cryptocrystalline varieties could be multihued.

Density
2.66 g/cm3

Mohs scale hardness
7 (but lower in adulterated varieties)