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Mineral. Crystals of serandite, natrolite, analcime, and aegirine from Mont Saint-Hilaire, Quebec, Canada. In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form. [1][2] The geological ...
Aquamarine variety of beryl with tourmaline on orthoclase. Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico. Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals. Austinite from the Ojuela Mine, Mapimí, Durango, Mexico. Ametrine containing amethyst and citrine, from Bolivia.
Sheets of mica Photomicrographs of a thin section containing phlogopite. In cross-polarized light on left, plane-polarized light on right. Dark mica from eastern Ontario. Micas (/ ˈ m aɪ k ə z / MY-kəz) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates.
Mineral (nutrient) Carbonic anhydrase, an enzyme that requires zinc (gray sphere near the center of this image), is essential for exhalation of carbon dioxide. In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, but most are not. [1][2][3] Minerals are one of the four groups of essential ...
Salt. Rock salt (halite) In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as rock salt or halite. Salt is essential for life in general, and saltiness is one of ...
The Minerals Portal. In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form. The geological definition of mineral normally excludes compounds that occur only in living organisms.
Emerald is a gemstone and a variety of the mineral beryl (Be 3 Al 2 (SiO 3) 6) colored green by trace amounts of chromium or sometimes vanadium. [2] Beryl has a hardness of 7.5–8 on the Mohs scale. [2] Most emeralds have many inclusions, [3] so their toughness (resistance to breakage) is classified as generally poor.
Obsidian (/ əbˈsɪdi.ən, ɒb -/ əb-SID-ee-ən ob-) [5] is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. [6] Obsidian is produced from felsic lava, rich in the lighter elements such as silicon, oxygen, aluminum, sodium, and potassium.