of
several colors. Its specimens of quartz crystals and beryl from the
Esmeralda mine attracted much attention when exhibited in San Diego,
and one of the pink beryls sold for $600 toward the close of the year.
The Mesa (irande Tourmaline Mining Company drove a tunnel more than 100
feet at a new mine and obtained some pink and green tourmaline. Work
had to be suspended, however, as the wet weather caused a cave in.
OTHER DISTRICTS IN SAN DIEGO COUNTY.
Mr.
Havis drove a tunnel on a new prospect near Banner and reported the
discovery of much lepidolite and some indicolite. Mr. Freeman has
developed his property near Vista by tunnels and crosscuts and has
obtained some gem tourmaline, chiefly of yellow and green color, with
some of a fine pink color. The Ramona gem district did not make much
progress, as there have been many lawsuits and much disagreement among
the mine owners. The district has, however, produced fine topaz and
pink beryl, besides spessartite, essonite, green tourmaline, and
aquamarine.
The
southern portion of the gem region in San Diego County has been
exploited by the San Diego Gem -Mining Company and the Mesa Grande
Consolidated Gold and Gem Mining Company. Essonite garnet, sold as
hyacinth, is the principal stone produced, and the demand for large,
clear, yellow stones has exceeded the production.
RIVERSIDE COUNTY.
Mr.
Bert Simmons has spent much time developing his claim at Oak Grove,
from which he obtained some pink and blue colored tourmalines. At his
new and promising claim at Chihuahua fine specimens of beryl and
indicolite have been found included in coarse albite. At Coahuila the
Mesa Grande Tourmaline Company and the Fano Kunzite-tourmaline Company
have been operating on hew prospects, and have produced some green
beryl and tourmaline. Mr. Robert Magee also has been successful in
working several deposits containing beautiful rubellite and beryl of
remarkable clearness.
The following notes abstracted from an article on The Pegmatite Veins of Pala, San Diego County, by Mr. G. A. Waring," are added to give further light on this interesting region:
The
gem district of San Diego County lies in a region of crystalline rocks
between the nearly level Mesa country on the west and the desert on the
east. The Palomares and higher mountains included in this area are
composed chiefly of mica schists, while the lower-lying hills and
mountains are of granite and diorite or gabbro. The relations seem to
be "intrusive diorite dikes and later granite intrusions within the
main granite mass." The gem minerals are found in pegmatite veins
cutting the diorite. The pegmatitic structure is well developed to the
northeast of Pala, where there is a gabbro boss about 1-1/2 miles wide
and 4 miles long inclosed in granite. The veins in this locality dip
rather uniformly to the southwest at an angle of about 30°. They have a
uniform banded structure, due to the presence of one band each of
graphic granite, coarse pegmatite, pay streak, and garnet quartzite.
The latter makes about half of the thickness of the vein. The pay
streak, which is composed of lepidolite, albite, musco-vite, and black
tourmaline, contains pockets lined with crystals and partly filled with
clay. The minerals of the pockets are clear and smoky quartz crystals
(often showing a development of rare faces), and, in some cases, rose
quartz and hyalite; albite in tabular crystals; orthoclase in
individual crystals embedded in the clay; greenish mus-covite;
lepidolite, often containing green tourmaline and kunzite. In some
cases the crystals attain large size in these pockets, although one
mineral may do so to the exclusion of another. Kunzite and tourmaline
are rarely found in the same pocket, though they occur in the same
vein. The clay of the pockets is found to consist of quartz,
