The halogens are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117, tennessine (Ts), may also be a halogen. In the modern IUPAC nomenclature, this group is known as group 17.
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
Potassium is a chemical element with the symbol K and atomic number 19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure. It was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals, all of which have a single valence electron in the outer electron shell, that is easily removed to create an ion with a positive charge – a cation, that combines with anions to form salts. Potassium in nature occurs only in ionic salts. Elemental potassium reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, and burning with a lilac-colored flame. It is found dissolved in sea water, and occurs in many minerals such as orthoclase, a common constituent of granites and other igneous rocks.
Feldspars are a group of rock-forming aluminium tectosilicate minerals, containing sodium, calcium, potassium or barium. The most common members of the feldspar group are the plagioclase (sodium-calcium) feldspars and the alkali (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust, and 41% of the Earth's continental crust by weight.
Orthoclase, or orthoclase feldspar (endmember formula KAlSi3O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles to each other. It is a type of potassium feldspar, also known as K-feldspar. The gem known as moonstone (see below) is largely composed of orthoclase.
Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi3O8 to CaAl2Si2O8), where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or 'record-groove' effect.
Potassium chloride is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt-like taste. Potassium chloride can be obtained from ancient dried lake deposits. KCl is used as a fertilizer, in medicine, in scientific applications, and in food processing, where it may be known as E number additive E508.
Sodium fluoride (NaF) is an inorganic compound with the formula NaF. It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux, and is also used in pesticides and rat poison. It is a colorless or white solid that is readily soluble in water. It is a common source of fluoride in the production of pharmaceuticals and is used to prevent dental cavities.
Fluoride or fluorine deficiency is a disorder which may cause increased dental caries and possibly osteoporosis, due to a lack of fluoride in the diet. Common dietary sources of fluoride include tea, grape juice, wine, raisins, some seafoods, coffee, and tap water that has been fluoridated. The extent to which the condition truly exists, and its relationship to fluoride poisoning has given rise to some controversy. Fluorine is not considered to be an essential nutrient, but the importance of fluorides for preventing tooth decay is well-recognized, although the effect is predominantly topical. Prior to 1981, the effect of fluorides was thought to be largely systemic and preeruptive, requiring ingestion. Fluoride is considered essential in the development and maintenance of teeth by the American Dental Hygienists' Association. Fluoride is also essential as it incorporates into the teeth to form and harden teeth enamels so that the teeth are more acid resistant as well as more resistant to cavity forming bacteria. Caries-inhibiting effects of fluoride were first believed to have been seen in 1902 when fluoride in high concentrations was found to stain teeth and prevent tooth decay.
Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi3O8). Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system. Orthoclase is a monoclinic polymorph stable at lower temperatures. At yet lower temperatures, microcline, a triclinic polymorph of potassium feldspar, is stable.
CharoiteK(Ca,Na)
2Si
4O
10(OH,F)•H
2O is a rare silicate mineral, first described in 1978 and named for the Chara River. It has been reported only from the Aldan Shield, Sakha Republic, Siberia, Russia. It is found where a syenite of the Murun Massif has intruded into and altered limestone deposits producing a potassium feldspar metasomatite.
Jennite is a calcium silicate hydrate mineral of general chemical formula: Ca9Si6O18(OH)6·8H2O.
Bararite is a natural form of ammonium fluorosilicate (also known as hexafluorosilicate or fluosilicate). It has chemical formula (NH4)2SiF6 and trigonal crystal structure. This mineral was once classified as part of cryptohalite. Bararite is named after the place where it was first described, Barari, India. It is found at the fumaroles of volcanoes (Vesuvius, Italy), over burning coal seams (Barari, India), and in burning piles of anthracite (Pennsylvania, U.S.). It is a sublimation product that forms with cryptohalite, sal ammoniac, and native sulfur.
Cesanite is the end member of the apatite-wilkeite-ellestadite series that substitutes all of apatite's phosphate ions with sulfate ions and balances the difference in charge by replacing several calcium ions with sodium ions. Currently very few sites bearing cesanite have been found and are limited to a geothermal field in Cesano, Italy from which its name is derived, Măgurici Cave in Romania, and in the San Salvador Island caves in the Bahamas.
Eveslogite is a complex inosilicate mineral with a chemical formula (Ca,K,Na,Sr,Ba)
48[(Ti,Nb,Fe,Mn)
12(OH)
12Si
48O
144](F,OH,Cl)
14 found on Mt. Eveslogchorr in Khibiny Mountains, on the Kola peninsula, Russia. It was named after the place it was found. This silicate mineral occurs as an anchimonomineral veinlet that cross-cuts poikilitic nepheline syenite. This mineral appears to resemble yuksporite, as it forms similar placated fine fibrous of approximately 0.05 to 0.005mm that aggregates outwardly. The color of eveslogite is yellow or rather light brown. In addition, it is a semitransparent mineral that has a white streak and a vitreous luster. Its crystal system is monoclinic and possesses a hardness (Mohs) of 5. This newly discovered mineral belongs to the astrophyllite group of minerals and contains structures that are composed of titanosilicate layers. Limited information about this mineral exists due to the few research studies carried out since its recent discovery.
Andrianovite is a very rare mineral of the eudialyte group, with formula Na12(K,Sr,Ce)6Ca6(Mn,Fe)3Zr3NbSi(Si3O9)2(Si9O27)2O(O,H2O,OH)5. The original formula was extended to show the presence of cyclic silicate groups and silicon at the M4 site, according to the nomenclature of eudialyte group. Andrianovite is unique among the eudialyte group in being potassium-rich (other eudialyte-group species with essential K are davinciite and rastsvetaevite). It is regarded as potassium analogue of kentbrooksite, but it also differs from it in being oxygen-dominant rather than fluorine-dominant. Also, the coordination number of Na in this representative is enlarged from 7 to 9. The name of the mineral honors Russian mathematician and crystallographer Valerii Ivanovich Andrianov.
Sheldrickite is a sodium calcium carbonate fluoride mineral, named in honor of George M. Sheldrick, former Professor of Crystallography at the University of Göttingen in Germany. Sheldrick is the creator of SHELLX computer program widely used for the analysis of crystal structures. Determination of the structure of this mineral required the software's capability of handling twinned crystals.
Canasite is a mineral whose name is derived from its chemical composition of calcium (Ca), sodium (Na), and silicon (Si). It was approved in 1959 by IMA.
Ganophyllite is a phyllosilicate mineral. It was named by Axel Hamberg in 1890 from the Greek words for leaf (φύλλον) and luster (γανωμα); the latter one was chosen due to the lustrous cleavages. The mineral was approved by the IMA in 1959, and it is a grandfathered mineral, meaning its name is still believed to refer to an existing species until this day. Tamaite is the calcium analogue, while eggletonite is the natrium analogue of said mineral.
Wöhlerite, also known as wöehlerite is a member of the amphibole supergroup, and the wöhlerite subgroup within it. It was named after German chemist Friedrich Wöhler. It was first described by Scheerer in 1843, but the crystal structure was later solved by Mellino & Merlino in 1979. Once approved, it was grandfathered by the IMA.
Radioactive 0.77% (K)