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16 THE PACIFIC MINERALOGIST

pectors have reached over to pick up
what appeared to be a shining nug-
get of scheelite, only to have the nug-
get come to life and squirm ouf of his
grasp. Scorpions, horned toads, liz-
ards, and snakes have a bright blue
or cream colored .fluorescence and
can be mistaken for fluorescent rocks
if a person is not careful. For this
reason it is a wise precaution to step
on the specimen before picking it
up.
Fluorescent analysis may be used
in many mines which do not contain Fo/ 'underground work a compact- assembly
scheelite. There are many forms of for a Mine1ralig1ht is provided by a Hot-Shot
zinc w hich fluoresce, and in certa in battery and a 6-:,volt tarnsformer s·uspe,nded
from hte shoulders. The picture illustrates
gold mines the use of the Mineralight an assembly of this: kind being used in
has proved of great advantpge in examination of a tungsten p,roperty.
grading the zinc and . throwing it out.
There are other mines which contain were located. Another company act-
fluorescent calcites or minerals as- ually placed over 100 tons of non-
sociated with the ore which is being bearing ore in its mill because it
mined, and in such cases the ultra- failed to use the ultra-violet light to
v iolet rays are used as a guide to check operations.
locate the vein that contains the The presence of an extremely
valuable ore. Hydrozincite, as well small quantity of mercury can very
as powellite, is minded by means of easily be determined with the Miner-
the fluorescence in many cases. alight, a Willemite screen and a
Hubnerite and wolframite are forms small flame for heating the sub-
of tungsten and in nearly every in- stance to be tested. The method was
·stance there are small areas of discovered by Dr. Wesley G. Leigh-
scheelite associated with these min- ton of Pomona College in 1935. He
erals. came upon this discovery by an ana--
In years of experience with ultra- 1 ytical line of reasoning. After theo-
violet rays used for mining purposes rizing what should occur, he carried
there have been many interesting on the experiments and found that
stories told concerning the appli- the facts actually were as he expect-
cation of ultra-violet rays. Four min- ed them to be. As little as l /1000 of
ing companies have discovered 1 per cent of mercury can be located
larger and more extensive deposits by this very sensitive test.
within a mile of the properties that Ultra-violet or black light fluores-
they once had thought to be the best cence is a fascinating subject. It has
in the locality. Another group had long ben used in crime detection and
stockpiled 60 tons of what they con- in many laboratory problems. Its
sidered to be their best ore. After use in mineralogy has been known
this work had been done they pur- for about 15 years, but its application
chased a short - wave ultra - violet commercially covers only the past
quartz lamp and found they had five years. New substances and
been working 40 feet from the rich- rocks are being constantly discov-
est part of the vein and they could ered and undoubtedly the commer-
have tripled the return from their cial application of ultra-violet to min-
labors if they had had a lamp to ing will be greatly extended in the
show them where the richest areas coming years.