Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1939-06-24
SUBSTRATA EYE DISCOVERS

Locations. Most are never reported
since few want a sudden wealth
source generally known. The above
merely indicate the accurate field
mapping possible to individuals by
/ this method.
Two Man Operation
Deep vein and channel survey
equipment consists Of two units set
up separately; an energizing trans
mitter with a vertical loop designed
10 swing in any compass direction
and a Null" tone finding receiver.
The former is supplied with alter
mating current Of approximately 175
kilocycles; me amount amplified
receiving the vertical distance pene-
trated A complete amplified re-
ceiving unit registers on sensi-
tive millimeter and in earphones.
Penetration steps are so, $50, ESQ
and $50 feet below the surface.
The deepest, $50 feet, is only for
instructed crew surveys requiring
a mOtor-generator power supply and
somewhat more extensive practice
over known ore bodies.
For field search the transmitting
loop is set up with the finder in
the loop plane and fifty to sever
al hundred feet distant depending
on the power chosen. Over neu-
trail or barren ground the Null"
receiver position is evenly horizon
tai. mineralized vein or lava COW
cred placer channel close to eth
er side tits the Null" in its d.
rection due to its secondary radia-
ton field. Crossing the vein shifts
this tilt to the opposite direction.
The intersection of these minimum
tone lines gives the approximate
depth to the upper ore body limits.
A series of setups made first
across the strike OF the main for
and later at right angles |
to the first indicate all main lodges |
and interesting veins Exact sta
ton points and Null" receiver tilt +
angles should be registered on a /
scale map drawn for reference. Cor
relation OF these successive dips
across an area portrays all con-
iuctiye veins, even though faulted,
heir depths and approximate de-
gree Of slope. AS barren veins do
lot contain any metal or sulfide
minerals 10 produce a secondary
ield, they do not register.
SINGLE PROSPECTING
Balanced Method
Here searches are made for
ingle and much smaller bodies of
METAL or ore Reconnaissance explo-
alton is both rapid and sure. The ]
ransmitter and receiver are held {
ogether on rigid handles and bal
need to the tone Null" This
hould always be done over neutral
round. Here point surveys Of an I
lyerted V Of ground beneath the
Derator are checked rather than \
ing veins axes. Because Of the S
IT loop positions and extreme SEN /
tivity the depth Limitation is TO '
Isl over twenty feet. c
Once assembled and properly ball
need the milliameter reads o. Sc
ctiye switches allow a choice OF
over and receiver sensitiyity. This
particularly useful in regions OF
frying naturalization found at diff
rent depths. The unsymetrical in
rsection Of the loop planes pro-
ices a broad lower field and
strlcted upper one. Immediate
,nefits Of such an arrangement
clude widening the effective
arch path on the surface as well
combining underground reactions
a single drift or shaft wall at
time. ri
Approaching a valued metallic ore
or buried treasure
uses a decided field shape distor- s.
On. indicating on the milliameter =
I'd including a loud tone in the
ZONES. The visual indicator read
g increases depending directly on
e area and amount OF the metal
mass encountered. Tone volume
yers an even broader range; small
concentrations giving a faint
r tone before any meter deflec-
IN occurs.
Walk Parallel Lines
In field search the operator walks
irly close parallel lines across an
ca checking all electrical indica-
ms on plotting map and stalking
cir ground positions. Indications