376 University of California Publications. [Geology
Joaquinite. Associated
with the minerals of the benitoite-bearing veins is occasionally found
a honey yellow or light brown substance in small generally individual
crystals or crystal grains rarely over one millimeter in diameter which
is believed to be a new mineral. On account of its rarity, minute size
and the general imperfectness of its crystals, its investigation has
been attended with considerable difficulty. A preliminary statement of
its properties is here presented. Some recently acquired material
containing this mineral is being worked over for its separation with a
view to a more complete study and for purposes of a quantitative
chemical analysis which has not heretofore been possible and the
writer expects to present a more complete description of the mineral
in the near future.
The
crystals are generally equant, occasionally slightly tabular, and
always show two parallel almost square smooth faces, the other larger
faces being strongly striated. The evidence so far obtained indicates
that the mineral is orthorhombie and the two broad smooth faces are
taken as the basal plane, and the eight lateral inclined planes, the
only pyramidal planes so far observed, are taken as the unit pyramid.
We have the combination c(001) and p(lll) and on one crystal a(100).
The axial ratios based on
