Also found in: Dictionary, Thesaurus, Wikipedia.
Related to Pyrophyllite: talc


AlSi2O5(OH) A white, greenish, gray, or brown phyllosilicate mineral that resembles talc and occurs in a foliated form or in compact masses in quartz veins, granites, and metamorphic rocks. Also known as pencil stone.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a mineral of the phyllosilicate class, with chemical composition Al2[Si4O10](OH)2; it contains admixtures of MgO, FeO, and Fe2O3. Pyrophyllite crystallizes in the mono-clinic system. It generally occurs in the form of foliate or compact scaly aggregates that are pale yellow, yellowish, or white in color. Pyrophyllite exhibits perfect cleavage. Greasy to the touch, it resembles talc. It has a hardness of 1–1.5 on Mohs’ scale and a density of 2,840 kg/m3.

Pyrophyllite deposits are usually associated with metamorphic rocks, in which the mineral forms packets of pyrophyllite slate or compact agalmatolite aggregates. It sometimes occurs in hydrothermal quartz and ore veins. Pyrophyllite is both fire- and acid-resistant. It is used commercially as a highly aluminiferous raw material for refractory products and as a chemically stable and insulating material.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
According to zeta potential measurement, minerals diaspore, kaolinite, illite and pyrophyllite, operating PZC diaspore, kaolinite, illite and pyrophyllite, were respectively about 6.68, 3.65, 2.88 and 2.51 [4]It was suggested to conduct the separation by using diaspore floatation method of kaolinite, illite and pyrophyllite, with a cationic collectors with a pH between 2 and 7.
For sintering, the conductive steel cap, pyrophyllite, and graphite sheet (as shown in Figure 1) are used, which can make sure that the samples received three-dimensional isostatic pressure and homogeneous current during the nanodiamond transformation process from OLCs.
[17] , in their study used pyrophyllite surface as adsorbent and found nearly complete removal (99.9%) at optimum adsorbent dose of 7g/L.
MD simulations of water at the basal plane surfaces of kaolinite and antigorite performed using DL_POLY_214 software (Smith and Forester, 1996) suggest that the silica tetrahedral face 001 should be hydrophobic, similar to pyrophyllite and talc, see Figure 9.
The gangue minerals in the veins are quartz, various carbonates, asbestiform and talcose silicates, and much more rarely pyrophyllite and the finely acicular borate szaibelyite.
(2001) augmented Bermans data by data for components of chlorite (amesite = [Mg.sub.4][Al.sub.2][Al.sub.2][Si.sub.2][O.sub.10]][(OH).sub.8], daphnite = [Fe.sub.5]Al[Al[Si.sub.3][O.sub.10]][(OH).sub.8]) and potassic white mica (pyrophyllite = [Al.sub.2][[Si.sub.4][O.sub.10]][(OH).sub.2], Mg-Al-celadonite = KAlMg[[Si.sub.4][O.sub.10]][(OH).sub.2], Fe-Al-celadonite = KAlFe[[Si.sub.4][O.sub.10]][(OH).sub.2]) and corresponding activity models for both phases.
Sugiyama K, Filio JM, Saito F, Waseda Y (1994) Structural change of kaolinite and pyrophyllite induced by dry grinding.
The economics of Talc & Pyrophyllite (9th edition, 2003) says that by far the largest markets for talc worldwide lie in paper and ceramics, each of which accounts for some 30% of total consumption of talc minerals.
These include the iron oxides, haematite and goethite; the sulphates jarosite, alunite and gypsum; clay minerals such as montmorillonite and kaolinite; phyllosilicates such as muscovite and illite; as well as pyrophyllite, chlorite, biotite, phlogopite, talc, carbonates, amphiboles, epidote, topaz, opaline silica and antigorite.
The belt press consists of cemented tungsten carbide piston cylinders supported by strong steel rings (belts) that are supported and sealed in a double-tapered cylinder by compressible composite gaskets of pyrophyllite stone and steel.
Wall-rock alteration is intense and consists of silicification, sericitization, chloritization, carbonatization, and kaolin, followed by epidotization with pyrophyllite. Silicification, chloritization, and sericitization are closely associated with Ag-Pb-Zn mineralization [18, 35].