Gypsum - Wikipedia. Gypsum. Selenite variety of gypsum. General. Category. Sulfate minerals. Formula(repeating unit)Ca. SO4. Elongated and generally prismatic crystals. Twinning. Very common on . A massive fine- grained white or lightly tinted variety of gypsum, called alabaster, has been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, Byzantine empire and the Nottingham alabasters of Medieval England. Mohs scale of mineral hardness, based on scratch. Hardness comparison, defines hardness value 2 as gypsum. It forms as an evaporite mineral and as a hydration product of anhydrite. Etymology and history. Upon addition of water, after a few tens of minutes plaster of Paris becomes regular gypsum (dihydrate) again, causing the material to harden or . Gypsum may act as a source of sulfur for plant growth, which was discovered by J. Mayer, and in the early 1. American farmers were so anxious to acquire it that a lively smuggling trade with Nova Scotia evolved, resulting in the so- called . When gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate, (bassanite, often simply called . As for anhydrite, its solubility in saline solutions and in brines is also strongly dependent on Na. Cl concentration. Selenite contains no significant selenium; rather, both substances were named for the ancient Greek word for the Moon. Selenite may also occur in a silky, fibrous form, in which case it is commonly called . Finally, it may also be granular or quite compact. Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 . It is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard. In hand- sized samples, it can be anywhere from transparent to opaque. A very fine- grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of various sorts. In arid areas, gypsum can occur in a flower- like form, typically opaque, with embedded sand grains called desert rose. It also forms some of the largest crystals found in nature, up to 1. Deposits are known to occur in strata from as far back as the Archaeaneon. GLOBAL INVESTMENT PERFORMANCE STANDARDS (GIPS. Hollis III, CFA Cutter Associates, Inc. United States Consultants Brian Henderson Hymans Robertson United Kingdom Ron Surz PPCA, Inc. Global IP Solutions Google acquired Global IP Solutions and its real time audio and video products and technology. The GIPS suite of products including: Voice Engine, Video Engine, Voice ConferencingEngine, Video ConferencingEngine, Voice. Hydrothermalanhydrite in veins is commonly hydrated to gypsum by groundwater in near- surface exposures. It is often associated with the minerals halite and sulfur. Gypsum is the commonest sulfate mineral. However, the unique conditions of the White Sands National Monument in the US state of New Mexico have created a 7. Its presence indicates oxidizing conditions. Under reducing conditions, the sulfates it contains can be reduced back to sulfide by sulfate- reducing bacteria. Electric power stations burning coal with flue gas desulfurization produce large quantities of gypsum as a byproduct from the scrubbers. Orbital pictures from the Mars Reconnaissance Orbiter (MRO) have indicated the existence of gypsum dunes in the northern polar region of Mars. Large open pit quarries are located in many places including Plaster City, California, United States, and East Kutai, Kalimantan, Indonesia. Several small mines also exist in places such as Kalannie in Western Australia, where gypsum is sold to private buyers for additions of calcium and sulfur as well as reduction of aluminum toxicities on soil for agricultural purposes. Crystals of gypsum up to 1. Naica Mine of Chihuahua, Mexico. The crystals thrived in the cave's extremely rare and stable natural environment. Temperatures stayed at 5. The largest of those crystals weighs 5. It can be used interchangeably with natural gypsum in some applications. Gypsum also precipitates onto brackish water membranes, a phenomenon known as mineral salt scaling, such as during brackish water desalination of water with high concentrations of calcium and sulfate. Scaling decreases membrane life and productivity. This is one of the main obstacles in brackish water membrane desalination processes, such as reverse osmosis or nanofiltration. Gips third-person singular simple present indicative form of whip Danish The third edition of the Global Investment Performance Standards (GIPS The 2010 Edition of the GIPS Standards Download the current GIPS standards (2010 edition) The GIPS standards are voluntary and based on the fundamental principles of full disclosure and fair representation of investment performance results. Other forms of scaling, such as calcite scaling, depending on the water source, can also be important considerations in distillation, as well as in heat exchangers, where either the salt solubility or concentration can change rapidly. A new study has suggested that the formation of gypsum starts as tiny crystals of a mineral called bassanite (Ca. SO4. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of TWA 1. TWA 5 mg/m. 3 for respiratory exposure over an 8- hour workday. It is also used in ameliorating high- sodium soils. Handbook of Mineralogy(PDF). V (Borates, Carbonates, Sulfates). Chantilly, VA, US: Mineralogical Society of America. Mindat^ ab. Klein, Cornelis; Hurlbut, Cornelius S., Jr. Borderland smuggling: Patriots, loyalists, and illicit trade in the Northeast, 1. Canadian Journal of Chemistry. Cement and Concrete Research. Bibcode: 2. 00. 7Geo.. G. Philosophical Transactions of the Royal Society A. Bibcode: 2. 00. 7RSPTA. C. An Introduction to the Rock Forming Minerals. The Albuquerque Journal. Retrieved 2. 7 January 2. University of Arizona^NASA Mars Rover Finds Mineral Vein Deposited by Water, NASA, 7 December 2. Natural Resources Canada. Retrieved 2. 7 January 2. London: The Telegraph. Retrieved 6 June 2. G.; Rodriguez- Blanco, J. D.; Ossorio, M.; Bots, P.; Garc. Bibcode: 2. 01. 2Sci.. V. Soil Science Society of America Journal. Retrieved 1. 5 December 2. United States Gypsum Company. Retrieved 1 March 2. Lesaffre Yeast Corporation. Retrieved 1 March 2. Applied Geochemistry, 2. American Mineralogist, 9. Crystal Growth & Design, 1.
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