The
mineral which is the subject of this note was discovered early in this
year by Mr. Hawkins and T. Edwin Sanders, who were prospecting- in the
southern part of the Mt. Diablo range, near the San Benito-Fresno
County line, about latitude 36Ξ’Β° 20'. If was first brought to the
writer's attention by Shreve & ComΞ’Βpany, who had purchased one of
the cut stones from a lapidary and who were later offered some of the
rough material as sapΞ’Βphire. They soon determined that it was not
sapphire but were unable to place it, and so sought the aid of the
University. SufΞ’Βficient material for the chemical analysis and for the
crystallo-graphic and other determinations was kindly supplied by Mr.
Hal Sanders of San Francisco, a brother of one of the original
discoverers. The writer is also indebted to Professor O'Neill for the
privileges of the chemical laboratory and for many courtesies.
As
the progress of the investigation has shown that it is a new mineral
species, it has been called benitoite, as it occurs near the head
waters of the San Benito River in San Benito County.
The most striking characteristic of the mineral is its blue color, and selected crystals cut in the right direction produce a
