Potassium feldspar glass

Potassium feldspar glass (Type D). A glass-ceramic with a glass matrix similar to that of feldspar, K20 Al203 6Si02, can contain 10-20 wt% glass phase. 

A wide variety of zeolites are known to form in saline lakes where the species present is dependent upon the chemistry of the solutions. Rapid zeolite formation is aided by the existence of the volcanic glass and high water salinities. Potassium feldspar occurs with the common alkali zeolites (Hay and Moiola, 1963 Hay, 1964 Hay, 1966 Sheppard and Gude, 1969, 1971), however, albite is not evident as a diagenetic mineral in saline lakes. 

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. 

The fusion of both potassium and sodium feldspar starts at about the same temperature however, the potassium feldspar melt has a higher viscosity which is maintained up to higher temperatures, so that the ceramic ware is not as readily deformed as when sodium feldspar is used. For this reason, potassium feldspars are preferred in ceramics, while the glass industry requires sodium feldspars which introduce both Na20 and AI2O3 into the glass batch. 

Older lacustrine deposits that contain interbedded saline minerals also show a correlation between the inferred salinity of the depositional environment and the authigenic mineralogy of tuffaceous sediments. In the Pleistocene deposits of Lake Tecopa, Calif. (120), glass is unaltered in tuff deposited in fresh water near the lake shore and inlets however, the tuffs consist chiefly of phillipsite, clinoptilolite, and erionite where deposited in moderately saline water and of potassium feldspar and searlesite where deposited in the highly saline water of the central part of the basin. Individual tuffs show a lateral gradation in a basinward direction of unaltered glass to zeolites and then to potassium feldspar with searlesite. A similar correlation between salinity and authigenic... 

Feldspar type of clay. Some clay deposits may include appreciable amounts of quartz. Commercial grades of clays may contain up to 20% quartz. Most abundant group of materials, composed of silicates of aluminium with sodium, potassium, calcium, and rarely barium. Most economically important mineral. Used for ceramics, glass, abrasive wheels, cements, insulation and fertilizer. 

In order to produce the various glasses, soda ash, salt cake, and limestone or lime are required to flux the silica. In addition, there is a contribution of lead oxide, pearl (as potassium carbonate), saltpeter, borax, boric acid, arsenic trioxide, feldspar, and fluorspar, together with a great variety of metallic oxides, carbonates, and the other salts required for colored glass. 

Sand, preferably fine particulate, is used as the source of Si02 in the manufacture of silicate glasses. Raw materials for the standard network-modifiers are lime, dolomite (CaC03 MgC03) for the alkaline earth oxides, sodium carbonate for sodium oxide, feldspar (sodium potassium calcium aluminum silicate), or other naturally occurring aluminum silicates, for aluminum oxide. Boron is used in the form of boric acid, borax and other boron minerals, e.g. ulexite (NaCa[B505(0H)6] 5H2O) or colemanite... 

Raw materials for glass wool sand, lime, dolomite, feldspar, kaolin, alumina-containing igneous rock, sodium carbonate, sodium sulfate, potassium carbonate, boron minerals... 

Durville F, Champagnon B, Duval E, Boulon G (1985) Ease spectroscopy of spinel microcrystallite in a Cr -doped silicate glass. J Phys Chem Solid 46 701—707 Erfurt G (2003) Infrared luminescence of Pb centres in potassium-rich feldspars. Phys Stat Sol (a) 200 429- 38... 

---