GEMS AND PRECIOUS STONES. 675
the
latter place there is a layer of light-gray quartzite carrying pyrite
and iron oxide stains. Above this is dark quartzite with pyrite, then a
few inches of soft shaly rock with limestone overlying. The lapis
lazuli was apparently found in the layer of dark quartzite. It is not
of good quality, being mixed with a number of other minerals difficult
of determination. Under the microscope in thin section two varieties oi
pyroxene, fine serieite, calcite, pyrite, clinozoisite, and other
minerals not identified, were observed besides bright-blue lazurite.
The matrix consists of a granular mass of these minerals with blue
lazurite as a filling in interstices. The specimen furnished by Mr.
Surr is about 2 inches thick, showing alternating bands of dark grayish
black, lighter gray, palo to dark bright blue, and yellowish streaks of
pyrite crystals. It is probable that the bands containing the most blue
could be cut into rather pretty matrix gems.
LAZULITE.
ARIZONA.
Specimens
of lazulite (false lapis lazuli) were received from Mr. James Shea and
Dr. Burt Ogburn, of Phoenix, Ariz., along with a few notes on its
occurrence. The deposit is about 12 miles north of Phoenix, in a small
hill near the edge of Paradise Valley. A good wagon road passes near
the locality. The lazulite is inclosed in quartzite, in which rock it
occurs disseminated in small grains and clusters and in larger crudely
shaped crystals. The matrix is white, gray, pinkish, brownish, and
greenish from staining. Fine mica or sericite has developed through the
quartzitic country rock, and some is associated with the lazulite. Of
the specimens seen, only a few could be cut into pure blue gems, but a
quantity would yield matrix stones showing dark ultramarine-blue
patches of various sizes. The presence of a little pyrite in small
crystals heightens the resemblance of this material to lapis lazuli.
OBSIDIAN.
UTAH.
A
small specimen of obsidian from Millard County, Utah, was received from
Mr. Maynard Bixby, of Salt Lake. This is glassy reddish brown with
jet-black streaks and patches through it. The black appear as rounded
spots in one position and as streaks in a position at right angles
showing the direction of flow of the molten volcanic glass. The mottled
effects of the brown and black are very pretty, and Mr. Bixby states
that this obsidian takes a high polish.
OPAL.
CALIFORNIA.
Two
deposits of opal have been prospected by F. M. Myrick, about 35 miles
east of Johannesburg, Cal. One of these is in the side of the same knob
as Lead Pipe Spring and about 100 yards northwest of the spring; and
the other is about a mile and a half to the northeast on the north side
of a steep hill slope. Only small prospects have been opened at each
locality.
