The plagioclase (Ab-An) series exhibits essentially complete solid solution at both high and low temperatures; coupled substitution of sodium and silicon by calcium and aluminum occurs. Luster. Description. If no EU harmonised classification and labelling exists and the substance was not registered under REACH, information derived from classification and labelling (C&L) notifications to ECHA under CLP Regulation is displayed under this section. Feldspar minerals have very similar structures, chemical compositions, and physical properties. Feldspars include three compositional endmembers: K-feldspar (KAlSi 3 O 8), albite (NaAlSi 3 … The REACH registered substance data and the C&L Inventory portal will be upgraded from the 9th November. conchoidal, uneven . Upon cooling, the first crystals that form from a melt with the composition X (= An50) will have the composition Y (approximately An83). The substance identifiers displayed in the InfoCard are the best available substance name, EC number, CAS number and/or the molecular and structural formulas. Microcline and orthoclase are potassium feldspars (KAlSi3O8), usually designated Or in discussions involving their end-member composition. Note that for readability purposes, only the pictograms, signal words and hazard statements referred in more than 5% of the notifications under CLP are displayed. Volumes 1 and 2 of Feldspar Minerals were published in 1974, but Volume 3 was not completed because I was forced to devote 3 years to the resolution of unforeseen problems in the construction of an ion probe. Please note that it may take a week or two to have everything fully in place, and please be aware in the meantime that the Registration status may be incorrect and the CLP regulatory context may be incompletely shown. For example, Or80 indicates that the mineral is composed of 80 percent KAlSi3O8 and 20 [i.e., 100 − 80] percent NaAlSi3O8.) With further cooling, in some cases the first and subsequently formed crystals will react continuously with the remaining liquid, thereby maintaining equilibrium; when the liquid becomes totally crystallized, the system will consist of homogeneous plagioclase crystals. In any case, feldspar crystals are relatively rare; almost all occur in miarolitic cavities, in pegmatite masses, or as phenocrysts within porphyries. Therefore, the key difference between quartz and feldspar is that the major chemical element present in quartz is silicon whereas in feldspar it is aluminum. pink, white, gray, brown. InfoCards are generated automatically based on the data available at the time of generation. Information on applicable regulatory frameworks is also automatically generated and may not be complete or up to date. Harmonised classification and labelling is a legally binding classification and labelling for a substance, agreed at European Community level. In cases in which such equilibrium is not maintained during cooling, the early and subsequently formed feldspars have different An contents. 21 November 2015 Prof. Dr. H.Z. An inorganic substance that is the reaction product of high temperature calcination in which aluminum oxide, barium oxide, calcium oxide, magnesium oxide, silicon oxide, and strontium oxide in varying amounts are homogeneously and ionically interdiffused to form a crystalline matrix. Although plagioclase grains in some rocks are essentially homogeneous, those in many rocks are zoned—i.e., different parts of individual grains have different Ab and An contents. The molecular structure is based on structures generated from information available in ECHA’s databases. This information is only displayed if the substance is well-defined, its identity is not claimed confidential and there is sufficient information available in ECHA’s databases for ECHA’s algorithms to generate a molecular structure. Harraz Presentation Feldspar Groups 10 Compositions A second group of alumino-silicates, tetrahedra form three-dimensional frameworks with Ca, Na and K as the balancing cations Feldspar is a common name that applies to a group of minerals with a general chemical formula of: xAl(Al,Si)3O8 where: x can be sodium (Na) and/or calcium (Ca) and/or potassium … They are discovered in igneous, metamorphic, and sedimentary rocks in all components of the sector. Experimentally, K-feldspar and other feldspar minerals are known to be good ice-nucleating agents, which play a significant role in atmospheric science. Those that have been recorded to occur as substitutions within the feldspar structures include lithium (Li), rubidium (Rb), cesium (Cs), magnesium (Mg), strontium (Sr), barium (Ba), yttrium (Y), ferrous iron (Fe 2+), thallium (Tl), lead (Pb), lanthanum (La) and other rare earth elements, and ammonium (NH 4) in the A position; and titanium (Ti), ferric (Fe 3+) and ferrous (Fe 2+) iron, boron (B), gallium … Close Find out more on how we use cookies. Mohs Hardness. Of these, substitution of some barium for potassium and some titanium or ferric iron or both for aluminum are especially common in alkali feldspars. White. Other relevant information includes the following: To see the full list of notified classifications and to get more information on impurities and additives relevant to classification please consult the C&L Inventory. Feldspar minerals have very comparable structures, chemical compositions, and bodily properties. Sanidine is a single-phase alkali feldspar; although frequently described chemically by the formula (K, Na)AlSi3O8, most analyzed specimens of sanidine range between Or50 and Or80. This substance has been found in the following regulatory activities (directly, or inheriting the regulatory context of a parent substance): Welcome to the ECHA website. In any case, perthite is the name properly applied to intimate mixtures in which the potassium feldspar component predominates over the plagioclase constituent, whereas antiperthite is the name given to intimate mixtures in which the plagioclase constituent is predominant. This information is only displayed if the substance is well–defined, its identity is not claimed confidential and there is sufficient information available in ECHA’s databases for ECHA’s algorithms to generate a molecular structure. Those that have been recorded to occur as substitutions within the feldspar structures include lithium (Li), rubidium (Rb), cesium (Cs), magnesium (Mg), strontium (Sr), barium (Ba), yttrium (Y), ferrous iron (Fe2+), thallium (Tl), lead (Pb), lanthanum (La) and other rare earth elements, and ammonium (NH4) in the A position; and titanium (Ti), ferric (Fe3+) and ferrous (Fe2+) iron, boron (B), gallium (Ga), germanium (Ge), and phosphorus (P) in the T position. Black Friday Sale! Feldspar is the most abundant mineral group in the Earth’s crust. The EC Number is the numerical identifier for substances in the EC Inventory. Vitreous. More information about Classification and Labelling is available in the Regulations section of ECHA website. Substances indicated, in 2009, as being intended to be registered by at least one company in the EEA. The molecular structure is based on structures generated from information available in ECHA’s databases. Many elements other than those required for the Or, Ab, and An end-member compositions have been recorded in analyses of feldspars. It does not represent a new labelling, classification or hazard statement, neither reflect other factors that affect the susceptibility of the effects described, such as duration of exposure or substance concentration (e.g. The Waste Framework Directive aims to protect the environment and human health from the generation and management of waste and to improve efficient use of resources. Chemical Formula. Warning! Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight. Occupational exposure limit (OEL) values are derived within two legal frameworks that form an integral part of the EU’s mechanism for protecting the health of workers. It is extracted from large granite formations. 6-6.5. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. There are more feldspars (60%) than all the other minerals combined in the outer (13-17) km of the crust. The ‘Hazard classification’ and labelling section uses the signal word, pictogram(s) and hazard statements of the substance under the harmonised classification and labelling (CLH) as its primary source of information. All the rock-forming feldspars are aluminosilicate minerals with the general formula AT4O8 in which A = potassium, sodium, or calcium (Ca); and T = silicon (Si) and aluminum (Al), with a Si:Al ratio ranging from 3:1 to 1:1. (This designation is used to specify the fractions of the constituents. Crystal System. Spat had long been used as the word for "a rock easily cleaved into flakes". Such notifications are required for hazardous substances, mixtures, or articles, manufactured or imported at over 1 kg per annum. Please upgrade your Internet Explorer to a newer version. Molecular structure. This site is not fully supported in Internet Explorer 7 (and earlier versions). The plagioclase series is essentially continuous at both high and low temperatures. The molecular formula identifies each type of element by its chemical symbol and identifies the number of atoms of each element found in one discrete molecule of the substance. Feldspars are aluminum silicates comprising barium, sodium, calcium, or potassium. The source of the information is mentioned in the introductory sentence of the hazard statements. The CAS number is the substance numerical identifier assigned by the Chemical Abstracts Service, a division of the American Chemical Society, to substances registered in the CAS registry database. in case of consumer and professional uses). Registration, Evaluation, Authorisation and Restriction of Chemicals, Chemical Agents Directive and Carcinogens or Mutagens Directive, EC Inventory, C&L Inventory, Pre-Registration process, Substances of very high concern identification, Recommendation for the Authorisation List, Getting started with EU chemicals legislation, Classification of substances and mixtures, Harmonised classification and labelling (CLH). That case, the early and subsequently formed feldspars have different an contents provided under this section based. Or in discussions involving their end-member composition not be complete or up to.. Studies ) than all the other minerals combined in the Earth ’ s physical, toxicological and hazard. Submitted to ECHA remains the responsibility of the end-members. minerals that make up over 50 % of ’... Their end-member composition to gather the widest possible range of scientific information for the regulatory processes ( C L! 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