1910–1911
Britannica 11th
Encyclopaedia Britannica · 11th edition
APOPHYLUTB, a mineral often classed with the zeolites, since it behaves like these when heated before the blowpipe and has the same mode of occurrence; it differs, however, from the zeolites proper in containing no aluminium. It is a hydrous potassium and calcium silicate, H;K.Ca4(Si()i)t+4jHjO. A small amount of fluorine is often present, and it is one of the few minerals in which ammonium has been detected. The temperature at which the water is expelled is higher than is usually the case with zeolites; none is gi…
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- Vol. 2, pp. 195-195