Bulletin . mon microclinewere noted, but not in commercial quantity. The various constituentsof this dike are more or less segregated, thus simplifying quarrying, butthe proportions of the different ingredients do not maintain sufficientuniformity to permit of a uniform material being obtained by takingthe run of the quarry. The microcline and albite pegmatites weresampled and analyzed, showing the following chemical compositions: Composition of microcline and of albite pegmatites from Chester Heights quarry. Ignition loss per cent. Si02 A1203 Fe203 do. Ti02 do :
Bulletin . mon microclinewere noted, but not in commercial quantity. The various constituentsof this dike are more or less segregated, thus simplifying quarrying, butthe proportions of the different ingredients do not maintain sufficientuniformity to permit of a uniform material being obtained by takingthe run of the quarry. The microcline and albite pegmatites weresampled and analyzed, showing the following chemical compositions: Composition of microcline and of albite pegmatites from Chester Heights quarry. Ignition loss per cent. Si02 A1203 Fe203 do. Ti02 do : 2. 75 MgO do Na20 K20 Microcline Albite pegmatite. pegmatite 99. 51 100. 46 The microcline pegmatite has a deformation range of 1,290° to1,310° C. and fuses to semi transparent glass of a faint cream tint. The albite pegmatite has a deformation range of 1,290° to 1,295°and fuses at 1,300° to a shapeless mass of white SKETCH MAP OF PARTS OF PENNSYLVANIA AND MARYLAND, SHOWING FELDSPAR DEPOSITS INVESTIGATED. FOR DESCRIPTION OF DEPOSITS SEE TABLE 2. CHEMICAL ANALYSES OF SAMPLES. 147 PROPERTIES IN STANDARD PORCELAIN MIXTURE. Microcline.—In the standard mixture the microcline pegmatite vitrifies at 1 300°and at 1,330° C. does not show warping. Fired at 1,330° it has a total shrinkage of cent, a cream color, and a translucency of The color is slightly inferior tothat of the standard trial. It is not altered under the raw-lead and fritted glazes. Albite.—In the standard porcelain mixture the albite pegmatite vitrifies at 1 300°and at 1,330° shows slight warping. Fired at 1,330° it has a total shrinkage of percent, a cream color, and a translucency of The color is a good white, but theporcelain is a characteristic soda-feldspar porcelain and lacks the brilliant fracture ofthe potash-feldspar porcelains. Under the raw-lead and fritted glazes the color isunaltere
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
