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Mineralati

Minerals

Quartz

SiO2

Also known as: Rock crystal

Quartz, Tibet.

JJ Harrison (https://www.jjharrison.com.au/) / CC BY-SA 2.5, via Wikimedia Commons · CC BY-SA 2.5 · Source

Overview

A common rock-forming mineral and the most abundant silica mineral in the crust.

Identification characteristics

  • Mohs hardness 7
  • Streak: White
  • Lustre: Vitreous

Formation and occurrence

Igneous, metamorphic and sedimentary environments

Common uses

Glass, electronics, abrasives

Varieties and members

Mineral

Amethyst
Mineral

Citrine
(United States Polar Rock Repository collection, Byrd Polar Research Center, Ohio State University, Columbus, Ohio, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 5500 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4. The simplest & most abundant silicate mineral in the Earth's crust is quartz (SiO2). All other silicates have silica + impurities. Many silicates have a significant percentage of aluminum (the aluminosilicates). Quartz (silicon dioxide/silica - SiO2) is the most common mineral in the Earth's crust. It is composed of the two most abundant elements in the crust - oxygen and silicon. It has a glassy, nonmetallic luster, is commonly clearish to whitish to grayish in color, has a white streak, is quite hard (H≡7), forms hexagonal crystals, has no cleavage, and has conchoidal fracture. Quartz can be any color: clear, white, gray, black, brown, pink, red, purple, blue, green, orange, etc. The pink coloration of rose quartz has been attributed to the presence of Ti+4 impurity or the presence of dumortierite-like fibers. Some rose quartz coloration has been attributed to radiation bombardment of quartz having Al and P impurities. Locality: small pegmatite body near the Reedy Glacier, Wisconsin Range, Transantarctic Mountains, Antarctica Photo gallery of quartz and rose quartz: www.mindat.org/gallery.php?min=3337 and www.mindat.org/gallery.php?min=3456 Mineral

Rose Quartz
Mineral

Smoky Quartz

Similar-looking specimens

Quarz, Calcit, Griewies, Rauris, Salzburg, Österreich Mineral

Calcite