350 University of California Publications. [Geology
The chemical analysis was kindly undertaken by Professor Blasdale. A and B were made on the blue material and C on the white.
From these is derived the formula BaTiSi202 which yields the following calculated values.
In
an attempt to account for the color of the mineral Bias-dale made
various qualitative tests, and reports: "A more careful examination of
a two-gram portion of the blue mineral failed to show the presence of
appreciable amounts of iron, cobalt, manganese, copper or chromium.
Very minute quantities of sodium and aluminum were obtained, but the
amounts were so small as to render it probable that they were derived
from the action of the reagents on the glass vessels employed rather
than from the mineral itself. Conclusive evidence of the presence of
the rarer earths, especially zirconium, tantalum and columbium. could
not be obtained. Careful examination of some of the mineral in a
delicate electroscope gave no indications of radioactivity." "It was
also shown that all the titanium was present in the higher degree of
oxidation. On dissolving the mineral in hydrofluoric acid in an
atmosphere of carbon dioxide a colorless solution was obtained which
failed to reduce potassium permanganate. ''
Benitoite
is considered by both of us a very acid titano-silicate. Blasdale
^notes that the formation of salts of an extremely acidic character is
not unusual when the acid concerned possesses very weakly acidic
properties and the base very strongly basic ones, also that silicon
dioxide possesses a remarkable tendency for the formation of complex
poly-acids and that it is not improbable that the very closely related
titanium dioxide might partially replace it atom for atom in such a
compound as the mineral under consideration. He suggests that the
