Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Quartz
open-in-new
<p>Quartz is a hard, <a href="/facts/Crystalline/e2R2mk3E">crystalline</a> <a href="/facts/Mineral/LkUFbNmv">mineral</a> composed of silica (<a href="/facts/Silicon_dioxide/A3WILp6J">silicon dioxide</a>). The <a href="/facts/Atom/FoQ4kGN5">atoms</a> are linked in a continuous framework of SiO4 silicon–oxygen <a href="/facts/Tetrahedral_molecular_geometry/583AL1sP">tetrahedra</a>, with each oxygen being shared between two tetrahedra, giving an overall <a href="/facts/Chemical_formula/hghUtthl">chemical formula</a> of <a href="/facts/Silicon_dioxide/A3WILp6J">SiO2</a>. Quartz is, therefore, classified structurally as a <a href="/facts/Silicate_mineral/WclrQW2I">framework silicate mineral</a> and compositionally as an <a href="/facts/Oxide_mineral/B4ajLX61">oxide mineral</a>. Quartz is the second most abundant <a href="/facts/Mineral/LkUFbNmv">mineral</a> in <a href="/facts/Earth/HLLmDfj0">Earth</a>'s <a href="/facts/Continental_crust/cGnK3oEr">continental crust</a>, behind <a href="/facts/Feldspar/DVvFnfA9">feldspar</a>. </p><p>Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are <a href="/facts/Chiral/hjx0eGrB">chiral</a>. The transformation from α-quartz to β-quartz takes place abruptly at 573 °C (846 K; 1,063 °F). Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. </p><p>There are many different varieties of quartz, several of which are classified as <a href="/facts/Gemstone/kHffmvE3">gemstones</a>. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of <a href="/facts/Jewellery/DYt7cj0R">jewelry</a> and <a href="/facts/Hardstone_carving/oMCDl7gn">hardstone carvings</a>, especially in Europe and Asia. </p><p>Quartz is the <a href="/facts/Mineral/LkUFbNmv">mineral</a> defining the value of 7 on the <a href="/facts/Mohs_scale_of_hardness/wXBMcVIm">Mohs scale of hardness</a>, a qualitative <a href="/facts/Scratch_hardness/5V7xkqar">scratch</a> method for determining the hardness of a material to abrasion. </p>