annual
report of the Geological Survey of West Australia for 1904 a the
existence of a precious opal at Coolgardie is described by the
government geologist, Mr. A. Gibb Maitland. His assistant, Mr. C. V. V.
Jackson, was sent to the locality to collect and report. The conditions
are peculiar, the opal occurring in a seam or belt of dark, compact,
slaty rock, thought to be a metamorphosed phase of the schists and
amphibolites of the district. The rock is full of joints and partings,
infiltrated with silica, which occupies small fissures and cavities,
both as quartz and as opal. The latter is chiefly of the common
variety, but is sometimes precious and of fine quality. The veinlets
are so small that little opal can be found suitable for cutting, yet in
places the cracks filled with opal form such a network that the whole
might be worked as a beautiful " matrix " stone. Mr. Maitland feels
doubtful as to the prospect of this locality being profitable on any
large or permanent scale.
OPAL PSEUDOMORPHS.
NEW SOUTH WALES.
In
the White Cliffs opal district of New South Wales there occur many
pseudo-morphous forms of opal after shells, crinoids, saurian bones,
and coniferous wood, and there are also curious masses of grouped
crystals, known locally as " fossil pineapples," representing the
replacement of some mineral not clearly determined.b A paper has lately appeared in regard to these problematic bodies. by Messrs. C. Anderson and H, Stanley Jevonsc
in which they present the results of a very careful study of some of
the best specimens obtained, and, after reviewing and dissenting from
the suggestions of previous writers (see Mineral Resources for 1901),
are led to believe that the original mineral must have been glauberite.
TURQUOISE.
CALIFORNIA.
In
the last report of this Bureau, in the special section devoted to the
gem minerals of California, the turquoise mines in the desert region of
San Bernardino County were described.d It was there stated
that these mines had produced a large amount of material, including
some stones of unusual size, but that nothing had been done in 1004.
Since then considerable quantities of material have been taken out,
including many stones of large size, which range from 50 to several
hundred carats. Some of the latter have sold as high as §1,500 each.
The color is mostly a pale shade, but it lias seemed to be popular, and
large quantities have been sold in the form of beads for necklaces,
etc., either of uniform size or graduated.
PERSIA.
The
old turquoise mines near Meshed, in eastern Persia, are still producing
quite extensively, notwithstanding the rude methods employed in working
them and the competition of the American mines. The registered exports
for last year had a value of £9,396, which may represent one-fourth of
the total output, as there is a continuous local demand and also
probably considerable smuggling. Every Persian must possess a
turquoise, good, bad, or indifferent, and fine stones
