Feldspar properties

We end this review of meteorite TL and CL and their relationship with feldspar properties with a brief description of some applications to several meteorite problems not previously mentioned. The details presented here are minimal, and intended to illustrate that even though our understanding of some of the basics is still incomplete, there is considerable potential for the application of the work to a variety of geological problems. 

Alumina in combination with siUca is present in limestone chiefly as clay, though other aluminum siUcates in the form of feldspar and mica may be found. When present in appreciable quantities, clay converts a high calcium limestone into a mad or argillaceous stone, which when calcined yields limes with hydrauhc properties. Limestones containing 5—10% clayey matter yield feebly hydrauHc limes those containing 15—30% produce highly hydrauHc limes. 

Sulfide collectors ia geaeral show Htfle affinity for nonsulfide minerals, thus separation of one sulfide from another becomes the main issue. The nonsulfide collectors are in general less selective and this is accentuated by the large similarities in surface properties between the various nonsulfide minerals (42). Some examples of sulfide flotation are copper sulfides flotation from siUceous gangue sequential flotation of sulfides of copper, lead, and zinc from complex and massive sulfide ores and flotation recovery of extremely small (a few ppm) amounts of precious metals. Examples of nonsulfide flotation include separation of sylvite, KCl, from haUte, NaCl, which are two soluble minerals having similar properties selective flocculation—flotation separation of iron oxides from siUca separation of feldspar from siUca, siUcates, and oxides phosphate rock separation from siUca and carbonates and coal flotation. 

The electrostatic separation method is the exclusive choice in some specific situations, for example in the cases of rutile and ilmenite deposits. These deposits generally contain minerals of similar specific gravities and similar surface properties so that processes such as flotation are unsuitable for concentration. The major application of electrostatic separation is in the processing of beach sands and alluvial deposits containing titanium minerals. Almost all the beach sand plants in the world use electrostatic separation to separate rutile and ilmenite from zircon and monazite. In this context the flowsheet given later (see Figure 2.35 A) may be referred to. Electrostatic separation is also used with regard to a number of other minerals. Some reported commercial separations include those of cassiterite from scheelite, wolframite from quartz, cassiterite from columbite, feldspar from quartz and mica, and diamond from heavy associated minerals. Electrostatic separation is also used in industrial waste recovery. 

Chemical potentials for the constituents of minerals are defined in a similar manner. All minerals contain substitutional impurities that affect their chemical properties. Impurities range from trace substitutions, as might be found in quartz, to widely varying fractions of the end-members of solid solutions series. Solid solutions of geologic significance include clay minerals, zeolites, and plagioclase feldspars, which are important components in most geochemical models. 

Part of this program was realized at the Survey. Between 1901 and 1907, the chemist Allen, the physicist Day, and the petrographer, Iddings, completed a rigorous study of the thermal properties of the plagioclase feldspars, the most abundant rockforming minerals. This study was important in several respects. 

Table 5.65 Thermodynamic properties of feldspar end-members in various structural forms according to Helgeson et al. (1978). Heat capacity function Cp= K + K Y +...

Carpenter M. A. (1988). Thermochemistry of aluminium/silicon ordering in feldspar minerals. In Physical Properties and Thermodynamic Behaviour of Minerals, E. K. H. Salje, ed. 265-323, D. Reidel Publishing Company. 

Carpenter M. A. and Ferry I M. (1984). Constraints on the thermodynamic mixing properties of plagioclase feldspars. Contrib. Mineral Petrol, 87 138-148. 

Smith I V. (1983). Some chemical properties of feldspars. In Reviews in Mineralogy, vol. 2 (2d ed.), P. H. Ribbe (series ed.), Mineralogical Society of America. 

Thompson J. B. Jr., Waldbaum D. R. and Hovis G. L. (1974). Thermodynamic properties related to ordering in end member alkali feldspars. In The Feldspars, W. S. MacKenzie and J. Zussman, eds. Manchester Manchester University Press. 

As one might expect there is an approximate correlation between the solid state structure and the physical properties of a particular silicate. For instance, cement contains discrete 8104 units and is soft and crumbly asbestos minerals contain double chains of 8104 units and are characteristically fibrous mica contains infinite layers of 8104 units, the weak bonding between the layers is easily broken, and micas show cleavage parallel to the layers and granite contains feldspars that are based on three-dimensional 8104 frameworks and are very hard. 

Yund, R.A. (1984) in Feldspars and Feldspathoids Structure, Properties and Occurrences (Ed. W.L. Brown), D. Reidel Publ. Comp., Dordrecht... 

Feldspar - [COAL] (Vol 6) - [CLAYS - SURVEY] (Vol 6) - [CLAYS - SURVEY] (Vol 6) -annual production of [MINERALS RECOVERY AND PROCESSING] (Vol 16) -ceramics [CERAMICS - ELECTRONIC PROPERTIES AND MATERIAL STRUCTURE] (Vol 5) -m coal cleaning [MINERALS RECOVERY AND PROCESSING] (Vol 16) -m limestone [LIME AND LIMESTONE] (Vol 15) -mica by-products [MICA] (Vol 16)... 

The distinctly differentiated results obtained, for example, for different faces of quartz or feldspar crystal, with clear observed differences depending on structure and compactness of the material under test, are an argument for wide use of the Mackensen blower in the study of engineering properties of rocks and ceramic materials and also in hardness estimation of minerals. 

The various members of the feldspar group show many characteristics in common. Crystallizing in the monoclime and irieiinie systems, they show similarity of crystal habit, cleavage and other physical properties as well as similar chemical relationships,... 

A clay mass is a mixture of clay and additives for a specific ceramic (processing) technique. The clay provides the plastic properties. Possible additives are a flux and a filler. Some examples of fluxes are potassium feldspar, bone meal, volcanic ashes and ground glass, all of which serve to affect the density and decrease the melting range. Fillers reduce the shrinkage as well as the sticky character of the clay. 

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