Quartz

Chemical Composition
SiO2 (Silicon Dioxide)

Physical Properties
Hardness (Mohs Scale): 7
Specific Gravity: 2.65
Crystal System: Trigonal
Fracture: Conchoidal
Color: Typically transparent or white, but can also appear in shades of purple (amethyst), yellow (citrine), and other colors depending on impurities.
Luster: Vitreous (glass-like)
Transparency: Transparent to translucent

Origin and Location
Quartz is found worldwide. Notable locations include:

Brazil (known for clear and amethyst quartz)
United States (especially Arkansas, known for clear quartz deposits)
Switzerland (famous for alpine quartz)
India (citrine and amethyst varieties)

Varieties
Clear Quartz: Colorless, transparent.
Amethyst: Purple quartz, colored by iron impurities.
Citrine: Yellow to golden quartz, often heat-treated amethyst.
Rose Quartz: Pink quartz, often associated with love and healing.
Smoky Quartz: Brown to black quartz, often used in jewelry.

Uses and Applications
Electronics: Used in quartz oscillators, watches, and clocks due to its piezoelectric properties.
Jewelry: Amethyst, citrine, and rose quartz are popular in gemstones and decorative jewelry.
Construction: As an aggregate in concrete and for sandblasting.
Glassmaking: Quartz is used in the production of glass.
Optical devices: Clear quartz is used in optical lenses.

Curiosities and Interesting Facts
Quartz is the most abundant mineral in the Earth's crust.
Amethyst has been historically associated with royalty and spirituality.
Quartz crystals have been used in ancient cultures for their believed healing and energy-amplifying properties.

Formation Process
Quartz forms in a variety of geological environments, primarily in igneous, metamorphic, and sedimentary rocks. It can crystallize from magma as it cools or form in veins within other rocks.

History and Discovery
Quartz has been used by humans since prehistoric times. It was used for making tools, weapons, and even as decoration in ancient civilizations. Its name originates from the Greek word "kryos", meaning "frozen," because ancient cultures thought it was ice that had been permanently frozen.

Optical Properties
Quartz has birefringent properties, meaning it can split light into two beams, making it useful in some optical applications.

Mineral Classification
Class: Silicates
Sub-Class: Tectosilicates
Group: Quartz Group