Instrumentation GDD Inc. 2018-11-09
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Pyrrhotite
often occurs in thin but continuous veins. It causes multiple and very high EM anomalies.
Chalcopyrite
is hardly detectable for two reasons.
1-
It is 20 times less conductive than pyrrhotite.
2-
It occurs, more often, in disseminated grains or clusters rather than in continuous beds, as the
pyrrhotite or graphite that extend in horizons of hundreds of meters.
Pyrite and galena
are not conductive when they respond to an EM survey even within a single crystal.
However, we have observed some very conductive samples of silver-bearing galena (Kamouraska) and
pyrite rich in gold. (Balmorals and Wrightbar mines).
Sphalerite, arsenopyrite and stibnite
are never conductive and are not detectable with EM and IP
surveys.
Rich graphite beds
can be more conductive than pyrrhotite. Occasionally they are not conductive at all.
Graphite can also show all intermediary conductivity values.
It is important to note that, with or without the presence of a conductor such as pyrrhotite, the MPP-
EM2S+ probe will measure the magnetic susceptibility value.
At all times, the MPP-EM2S+ provides an estimated EM conductivity value.
2. Mineral Conductivity – General Rules
