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THE PACIFIC MINERALOGIST 7

writer first visited on a LAMS trip, geodes. Solid quartz cores and hol-
are well known to LAMS tripsters, low cored geodes covered with fine
, but thought worthy of mention by scintillating xl coating. Silica or in-
the editor for their interest to the distinctly fine or micro-xl quartz in
newer members. the bull quartz matrix of the iron
Mimeographed skeches of miner- pyrite ore from Governor mine. Many
al locations and descriptions of min- specimens disintegrated to 'sugar'
erals to be found might be a desir- quartz. Pure silica or quartz as
able supplement to services already clear as a window pane may be a
extended to the members through the valuable gold bearing ore yielding
Pacific Mineralogist. :If some mem- high values in invisible free flour
ber would work out a simple and and flake gold or grayed with silver.
positive chemical qualitative assay Large deposits of silica are valu-
test for the presence of gold which able and in demand on West Coast
could be used by school clubs in for glass manufacturing.
selecting the specimens brought in
by students which are worth the Ribbon Agate Geode Gemstones.
price of a quantitative assay, it The ribbon agate geode deposits visi-
would be a great help. The aqua ted are among the finest in the coun-
regia and other field tests described try. Solid geodes are called nodules
in the University of Arizona bulletin and are exceptionally fine cutting
on Field Tests for the Common Metals material yielding settings in a variety
(No. 147, price 15c, Tucson) though of shades of cobalt blue and white.
it includes some of the finest de- The silica is deposited by cooling
scriptions available, do not seem to mineral waters from great depths,
w ork satisfactorily, due principally bearing different stains for different
to the three or four hour digesting periods of time, forming rings from
time required by heating in water outside in. If deposition closes pas-
bath. ' sage flow, balance of silica deposit
Possibly someone could also indi- will be in form of qu_artz xls, filling or
cate how a metal shop gas furnace partially filling cavity. Nodules of
could be used as a muffle furnace solid banded aga te are formed on
in assay tests by school clubs. There underside of geodes, or a portion of
must be a great number of such the geode will show bedding. planes
problems wherein we can all help of seasonal or periodic deposit. Pro-
each other greatly. Another Uni- cess may take only a few months or
versity of Arizona bulletin which a number of years. It is the same
was found of greatest value in con- process that goes on when agate
nection wtih school mineral clubs, replaces wood or other cellulose or
and which with the one above were soluble minerals. Geodes are thought
purchased by a considerable num- to be formed in gas voids in basalt
ber of the members, is Bulletin 139 deposits. Basalt is formed on the
by Butler, on "Some Facts About surface then buried to depths where
Ore Depositis," price 15c including underground mineral waters fill voids
mailing charges. with agate and quartz silica deposits,
then brought to the surface again
Minerals of Mint Canyon -- by later earth deformations. Basalt
Pyrite. Auriferous (gold bearing) weathers away and decomposes,
Iron sulfides. "Fool's Gold." Axiom leaving geodes. Basalt with agate
of mineralogy: "Whe~ever there's filled voids is to be found in this
py rite there's gold." Every iron location. The small agate nodules
stained specimen worth an assay. coated with green griffithite noted
Quartz XLS. Large or distinct later.
quartz crystals in cores of agate (Continued on page 19)