Mining_Methods_UnderGround_Mining - Mining and Blasting

Mineral prospecting and
exploration
Finding orebodies
For a geologist in the mining business,
exploiting an orebody is the
easy part of the job. The hardest
part is to find the orebody and define
it. But how do you find these
accumulations of metallic miner-
als in the earth's crust? The mining
company has to ensure that an ore-
body is economically viable, and
needs a guarantee of ore production
over a very long period of time,
before it will engage in the heavy
investment required to set up a
mining operation. Even after production
starts, it is necessary to
locate and delineate any extensions
to the mineralization, and
to look for new prospects that
may replace the reserves being
mined. Investigating extensions,
and searching for new orebodies,
are vital activities for the mining
company.
Prospecting
Prospecting involves searching a district
for minerals with a view to further operation.
Exploration, while it sounds similar
to prospecting, is the term used
for systematic examination of a deposit.
It is not easy to define the point where
prospecting turns into exploration.
A geologist prospecting a district is
looking for surface exposure of minerals,
by observing irregularities in co-
lour, shape or rock composition. He uses
a hammer, a magnifying glass and some
other simple instruments to examine
whatever seems to be of interest. His
experience tells him where to look, to
have the greatest chances of success.
Sometimes he will stumble across ancient,
shallow mine workings, which
may be what led him to prospect that
particular area in the first place.
Soil-covered ground is inaccessible
to the prospector, whose first check
would be to look for an outcrop of the
mineralization. Where the ground cover
comprises a shallow layer of alluviums,
Gold panning in the wind.
trenches can be dug across the mineralized
area to expose the bedrock. A
prospector will identify the discovery,
measure both width and length, and
calculate the mineralized area. Rock
samples from trenches are sent to the
laboratory for analysis. Even when minerals
show on surface, determining any
extension in depth is a matter of qualified
guesswork. If the prospector's
findings, and his theorizing about the
probable existence of an orebody are
solid, the next step would be to explore
Mineral PrOSPeCTing and exPlOraTiOn
the surrounding ground. Exploration
is a term embracing geophysics, geochemistry,
and also drilling into the
ground for obtaining samples from any
depth.
geophysical exploration
From surface, different geophysical me-
thods are used to explore subsurface formations,
based on the physical properties
of rock and metal bearing minerals
such as magnetism, gravity, electrical
underground mining methods 13