The alteration ones are represented by rocks in which the mineral assemblage of the partly altered peridotites olivine clinopyroxene serpentine brucite and spinel-group minerals has been altered to serpentine carbonate and talc
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The alteration ones are represented by rocks in which the mineral assemblage of the partly altered peridotites olivine clinopyroxene serpentine brucite and spinel-group minerals has been altered to serpentine carbonate and talc
Talc The term talc covers a wide range of natural rocks and minerals most of which are magnesium silicates. Talcs tend to form in plates. You can see the platy nature of talc from this Scanning Electron Micrograph SEM taken at a 5000 times magnification. This platy structure gives talc many of its reinforcing performance properties in plastics
Dense high-purity talc is called steatite. It is a metamorphic mineral found in veins and magnesium-rich rocks. It is often associated with serpentine tremolite and forsterite and occurs as an alteration product of silica-poor igneous rocks. Talc is widespread and is found in most areas of the world where low-grade metamorphism occurs
Talc is found as a metamorphic mineral in veins in foliated masses and in certain rocks. It is often associated with serpentine tremolite forsterite and almost always with carbonates calcite dolomite or magnesite in the lower metamorphic facies. It also occurs as an alteration product as from tremolite or
2018-8-23Talc Talc is the softest mineral demonstrated by its position at the bottom of Mohs Scale of Hardness with a relative hardness value of 1. It has a soapy greasy feel. Talc is formed by the hydrothermal alteration of ultrabasic rocks or low grade thermal metamorphism of siliceous dolomites
Effects of magmatic processes serpentiniation and talc-carbonate alteration on sulfide mineralogy and ore textures in the Black Swan disseminated nickel sulfide
2012-3-7arrangement of hydrothermal alteration ones and recognition of this arrangement may provide information useful in mineral exploration and may in some cases provide vectors to undiscovered deposits. Third hydrothermal alteration can provide key information on
Talc-carbonate alteration of some basic and ultrabasic intrusions in Cornwall. the observed mineral assemblages being controlled by hydrothermal alteration. Enrichment in As is closely related
2019-4-9author to suspect the presence of talc in the mineral most probably as an alteration product and it was indeed found to be so. The alteration of tre- molite to talc seemed to be due to meteoric solutions and to the atmosphere because the alteration was found to be always a
Talc is a hydrothermal and metamorphic mineral which is found typically in the green schist facies of metamorphic rocks and also in shear ones where it is an alteration area. Talc has recently been found to be widespread in limestones of many formations that is ranging in age from Devonian till Recent
Talc is present in cracks and as alteration of pyroxenes. Samples have been chosen from the fresh rock 114 to the base of the ochreous ferruginous layer 95 Talcs have been studied in thin sections by XRD electron microprobe CAMEBAX BRGM Orleans France and by STEM on 2 i particles BADAUT 1981 DUPLAY 1982
The pure talc mineral is a hydrous magnesium silicate Mg3Si3O10OH2 which theoretically is 31.7 percent MgO 63.5 percent SiO2 and 4.8 percent H2O. The crystal structure of pure talc is a brucite sheet Mg12O12H4 sandwiched between two silica SiO2 sheets to form talc layers that are superimposed indefinitely
Si-metasomatism in serpentinied peridotite The effects of talc-alteration on strontium and boron isotopes in abyssal serpentinites from Hole 1268a ODP Leg 209. Mineral major element analyses were performed at the University of Leeds using a Jeol JXL 8230 Superprobe. An
Talc is an alteration mineral. It is formed by geological modification of some host rock. Most talc is formed from the alteration of dolomite CaMgCO32 or magnesite MgO in the presence of
Alteration of dolomite to talc will also modify the porosity and permeability of carbonate hydrocarbon reservoirs 2931. The silica required for the mineral alteration can be provided by either silica-rich hydrothermal fluids or silica e.g. quart chert and opal within the carbonate reservoirs
2009-3-23the oetahedral layer of stevensite converts this mineral to tale concomitantly freeing interlayer cations and water. Stevensite is unstable and is converted to talc above a temperature of 275 at water pressures of 690 bars. It is believed that hydrothermal alteration of wollastonite took
Olivine phenocrysts are totally replaced by Fe oxyhydroxide andor a pale yellowish mineral identified in thin section as a mixture of mostly chlorite talc clay and Fe oxyhydroxide Figs. F10 F11. Plagioclase phenocrysts commonly are clay lined along crosscutting fractures but are otherwise fresh
2008-12-9ground talc sample Fig.3a. A mass loss observed by TG Fig.3b in the range 900-1000C characteried the loss of structural water due to dehydroxylation of the ground talc. Fig.4 depicts the ETA results used to characterie the effect of grinding on the thermal behaviour of the natural talc mineral. The ETA results are presented in Fig.4 as
2011-6-25In addition to alteration to serpentine and talc olivine may also alter to a reddish brown very fine-grained mass that pseudomorphs the original grain Called iddingsite Not a single mineral a fine-grained integrowth Product of low temperature alteration Mg
2020-5-18The chemical name for the substance of quart is silica and any mineral that is composed in part of silica is a silicate. In the Classification of Silicate Minerals and the study of minerals and rocks silica is called an acid in silicates the substances other than silica are called bases for example lime potash and soda. When giving the full name of a silicate the names of these bases