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In chemistry, a carbide usually describes a compound composed of carbon and a metal. In metallurgy, carbiding or carburizing is the process for producing carbide coatings on a metal piece.
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO• is the hydroxyl radical. The corresponding covalently bound group –OH of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.
The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula XY(Si,Al)2O6, where X represents calcium (Ca), sodium (Na), iron or magnesium (Mg) and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium (Cr), aluminium (Al), magnesium (Mg), cobalt (Co), manganese (Mn), scandium (Sc), titanium (Ti), vanadium (V) or even iron. Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a common structure consisting of single chains of silica tetrahedra. Pyroxenes that crystallize in the monoclinic system are known as clinopyroxenes and those that crystallize in the orthorhombic system are known as orthopyroxenes.
Ulexite (NaCaB5O6(OH)6·5H2O, hydrated sodium calcium borate hydroxide), sometimes known as TV rock or Television stone, is a mineral occurring in silky white rounded crystalline masses or in parallel fibers. The natural fibers of ulexite conduct light along their long axes, by internal reflection. Ulexite was named for the German chemist Georg Ludwig Ulex (1811–1883) who first discovered it.
A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the mineral called perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). 'A' and 'B' are two positively charged ions (i.e. cations), often of very different sizes, and X is a negatively charged ion (an anion, frequently oxide) that bonds to both cations. The 'A' atoms are generally larger than the 'B' atoms. The ideal cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite forms may exist where either/both the A and B sites have a configuration of A1x-1A2x and/or B1y-1B2y and the X may deviate from the ideal coordination configuration as ions within the A and B sites undergo changes in their oxidation states.
An oxyanion, or oxoanion, is an ion with the generic formula A
xOz−
y. Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound H
zA
xO
y. The structures of condensed oxyanions can be rationalized in terms of AOn polyhedral units with sharing of corners or edges between polyhedra. The oxyanions adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology.
Pauling's rules are five rules published by Linus Pauling in 1929 for predicting and rationalizing the crystal structures of ionic compounds.
A uranate is a ternary oxide involving the element uranium in one of the oxidation states 4, 5 or 6. A typical chemical formula is MxUyOz, where M represents a cation. The uranium atom in uranates(VI) has two short collinear U–O bonds and either four or six more next nearest oxygen atoms. The structures are infinite lattice structures with the uranium atoms linked by bridging oxygen atoms.
In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central ion/molecule/atom is called a ligand. This number is determined somewhat differently for molecules than for crystals.
Calcium hexaboride (sometimes calcium boride) is a compound of calcium and boron with the chemical formula CaB6. It is an important material due to its high electrical conductivity, hardness, chemical stability, and melting point. It is a black, lustrous, chemically inert powder with a low density. It has the cubic structure typical for metal hexaborides, with octahedral units of 6 boron atoms combined with calcium atoms. CaB6 and lanthanum-doped CaB6 both show weak ferromagnetic properties, which is a remarkable fact because calcium and boron are neither magnetic, nor have inner 3d or 4f electronic shells, which are usually required for ferromagnetism.
Julgoldite is a member of the pumpellyite mineral series, a series of minerals characterized by the chemical bonding of silica tetrahedra with alkali and transition metal cations. Julgoldites, along with more common minerals like epidote and vesuvianite, belong to the subclass of sorosilicates, the rock-forming minerals that contain SiO4 tetrahedra that share a common oxygen to form Si2O7 ions with a charge of 6- (Deer et al., 1996). Julgoldite has been recognized for its importance in low grade metamorphism, forming under shear stress accompanied by relatively low temperatures (Coombs, 1953). Julgoldite was named in honor of Professor Julian Royce Goldsmith (1918–1999) of the University of Chicago.
Zemannite is a very rare oxide mineral with the chemical formula Mg0.5ZnFe3+[TeO3]3·4.5H2O. It crystallizes in the hexagonal crystal system and forms small prismatic brown crystals. Because of the rarity and small crystal size, zemannite has no applications and serves as a collector's item.
Dicopper chloride trihydroxide is the chemical compound with the formula Cu2(OH)3Cl. It is often referred to as tribasic copper chloride (TBCC), copper trihydroxyl chloride or copper hydroxychloride. It is a greenish crystalline solid encountered in mineral deposits, metal corrosion products, industrial products, art and archeological objects, and some living systems. It was originally manufactured on an industrial scale as a precipitated material used as either a chemical intermediate or a fungicide. Since 1994, a purified, crystallized product has been produced at the scale of thousands of tons per year, and used extensively as a nutritional supplement for animals.
Donnayite-(Y) is a rare-earth carbonate mineral containing the rare-earth metal yttrium. It was first discovered in 1978 at Mont Saint-Hilaire, Quebec. Donnayite was subsequently identified and named after Joseph D. H. Donnay and his wife, Gabrielle Donnay. Both were prominent mineralogists and crystallographers, and J. D. H. Donnay was awarded the Roebling Award by the Mineralogical Society of America in 1971 for his emphasis on the importance of optical mineralogy and crystal morphology. Donnayite tends to occur in small quantities in the pegmatite dykes and miarolitic cavities of mountainous regions. It crystallizes in this environment with increasing alkalinity values until the alkalinity suddenly drops during the last stage of crystallization. This results in increasing amounts of Na carbonates and REE minerals. First discovered at Mont St-Hilaire, donnayite has since been found in the Southern Ural Mountains of Russia and the Narssarssuk pegmatite of South Greenland. Donnayite crystals tend to be small and the color is commonly pale yellow to yellow with a white streak and a vitreous luster. Donnayite crystals usually display trigonal or hexagonal symmetry and have a hardness of 3. Twinning is extremely common in this mineral. Minerals closely related to donnayite include synchysite, calcite, sphalerite, microcline, and analcime. Donnayite is isomorphous with weloganite and mckelveyite.
Carlosruizite is a sulfate or selenate – iodate mineral with chemical formula: K6(Na,K)4Na6Mg10(SeO4)12(IO3)12·12H2O. It has a low density (specific gravity of 3.36), colorless to pale yellow, transparent mineral which crystallizes in the trigonal crystal system. It forms a series with fuenzalidaite.
The spinels are any of a class of minerals of general formulation AB
2X
4 which crystallise in the cubic (isometric) crystal system, with the X anions arranged in a cubic close-packed lattice and the cations A and B occupying some or all of the octahedral and tetrahedral sites in the lattice. Although the charges of A and B in the prototypical spinel structure are +2 and +3, respectively, other combinations incorporating divalent, trivalent, or tetravalent cations, including magnesium, zinc, iron, manganese, aluminium, chromium, titanium, and silicon, are also possible. The anion is normally oxygen; when other chalcogenides constitute the anion sublattice the structure is referred to as a thiospinel.
The mineral hubeite, Ca
2Mn2+
Fe3+
[Si
4O
12(OH)]·(H
2O)
2, is a sorosilicate of the Si
4O
13 group. Structurally it also belongs to the Akatoreite group. It was found and named after the province of Hubei, China. It is common to iron ores in a mine of that region. It occurs mainly as aggregates of fan like crystals. It is dark to pale brown, has orange-brown streak and is vitreous. Hubeite has a hardness of 5.5 in the Mohs scale, one good cleavage and conchoidal fracture. It is triclinic with a space group of P1*. The structure of hubeite is very uncommon, and in fact there is only one other mineral that fits the Si
4O
13 group, which is ruizite.
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.
Coupled substitution is the geological process by which two elements simultaneous substitute into a crystal in order to maintain overall electrical neutrality and keep the charge constant. In forming a solid solution series, ionic size is more important than ionic charge, as this can be compensated for elsewhere in the structure.
Meyrowitzite, Ca(UO2)(CO3)2·5H2O, is a carbonate mineral verified in May of 2018 by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association. It is an extremely rare mineral, discovered in the Markey mine Utah, U.S.A. The mineral is a transparent yellow and has blades up to approximately 0.2 mm in length. It is soluble in water or aqueous solutions. Meyrowitzite is named in honor of Robert Meyrowitz (1916-2013), an American analytical chemist. After serving in WW II, he joined the United States Geological Survey (USGS). He was known for developing innovative new methods for analyzing small and difficult to study mineralogical samples along with his formulation of the high-index immersion liquids.
References
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID 235729616.
- ↑ Cooper, Mark A.; Hawthorne, Frank A.; Roberts, Andrew C.; Grice, Joel D.; Stirling, John A.R.; Moffatt, Elizabeth A., 1998, American Mineralogist, Volume 83, pp 390-399
- ↑ . Minsocam.org. Retrieved on 2015-10-20.
- 1 2 3 4 5 6 7 8 9 10 Cooper, Mark A.; Hawthorne, Frank C.; Roberts, Andrew C.; Grice, Joel D.; Stirling, John A.R.; Moffatt, Elizabeth A. (1998). "Georgeericksenite, Na6CaMg(IO3)6(CrO4)2(H2O)22" (PDF). American Mineralogist. Retrieved October 15, 2015.