Mining of large deposits over an extensive area
requires one of a variety of extraction methods. There are
different types of mines to obtain raw material, and it depends on the
shape and type of deposits. The types of mining can be grouped into
surface mining and subsurface mining.
Surface methods are the simplest and cheapest. Some deposits like
coal, gypsum, and oil shale are deposited in relatively flat and
continuous areas. These products are found in beds or seams that
are between layers of rock. The material above the seam is called the overburden.
The overburden can be removed if it is not too deep and create an open
pit or strip mine.
Subsurface mining techniques are dependant on how deep the
deposits are. Some veins of gold will branch off into many directions. Excavating
these types of deposits can be very dangerous.
Removing the overburden
Opening to subsurface mine