AN ANALCITE-BASALT FROM COLORADO 693 
all monchiquites would have yielded analcite-basalt on crystalliza- 
tion, for the ratio of SiO, : Al,O, : R,O0 : H,O must probably 
be vety neatly/4.; 131: 21\in order that this unusual rock con- 
stituent may form. With lower silica, nepheline and analcite, 
or glass, would presumably result. 
WHITMAN Cross. 
