Feldspar, aplite

BOSTONITE. A rather rare rock type, dense, with an occasional feldspar phenocrysl and grayish in color, II is composed almosl wholly of alkaline feldspar, being analogous to aplites. The type locality is Salem Neck, Massachusetts, close to Boston, for which it was named. 

Elba island 8.5-6.8 - Monzogranites and minor granodiorites, sieno-granites, alkali feldspar granites, aplites and pegmatites forming stocks, laccoliths, dykes and sills. Late (5.8 Ma) calc-alkaline mafic dike. 

Aplite Alkali lime feldspar Varies with exact composition... 

Of the approximately 5 million metric tons of feldspar prodncts produced annually, Italy is the leading supplier with about 29%, followed by the US with about 12%. Other major producers are Japan (aplite), France, Germany, Korea, and Thailand. The two major applications for feldspar worldwide are glass and ceramics, which rely more on feldspar chemistry than mineralogy. In the US, 54% is used in glass and 44% in ceramics. 

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