and rocks. For example, they might test rocks to see if the rocks are magnetic or contain
certain chemical elements. Then, geologists make maps of their findings to locate possible
ore deposits. Today, satellites do some of the work for geologists. Satellites can make maps
of large areas more quickly than geologists on the ground can.
After a mineral deposit is found, geologists determine how big it is. They also calculate how
muchof the valuableminerals they think they will get from mining the deposit. The minerals
will only be mined if it is profitable. If is profitable to mine the ore, they decide the way
it should be mined. The two main methods of mining are surface mining and underground
mining.
Surface Mining
Surface mining is used to obtain mineral ores that are close to Earth’s surface. The soil and
rocks over the ore are removed by blasting. Typically, the remaining ore is drilled or blasted
so that large machines can fill trucks with the broken rocks. The trucks take the rocks to
factories where the ore will be separated from the rest of the rock. Surface mining includes
open-pit mining, quarrying, and strip mining.
As the name suggests, open-pit mining creates a big pit from which the ore is mined.Figure
3.27shows an open-pit diamond mine in Russia. The size of the pit grows until it is no longer
profitable to mine the remaining ore. Strip mines are similar to pit mines, but the ore is
removed in large strips. A quarry is a type of open-pit mine that produces rocks and minerals
that are used to make buildings.
Figure 3.27: This diamond mine is more than 600 m deep. ( 21 )