Important Cooling Process

The world has a solid core of nickel and iron which is surrounded by a mantle of molten rock. That which is called magma is when this material forces itself into the many cracks and other points of weakness in the crust. These tongues of molten rock, which spread out in many different directions, heat the surrounding rock, they alter it and, in some occasions, they cause it to re-melt. The entire mass then cools off and that is when the minerals, some of which are very valuable, start to crystallize.

Mineral constituents of molten lava crystallize at varied temperatures. The result of this is that they tend to concentrate during the cooling process. These concentrations are what most of the time create mineral deposits. The composition of magma changes as each different mineral crystallizes out of the magma. The weightier minerals sink to the bottom of the semi-liquid mass and are concentrated in a process commonly known as magmatic segregation. Some magmas do not have valuable minerals, but still other magmas hold mineral deposits which are economically exploitable.

Other deposits can be formed by minerals which are dissolved in the circulating liquids in and around magmas; these minerals are redeposited at some place where chemical and physical conditions permit them to be. These processes are known by the name of hydrothermal processes.

Another important source of lead, copper and zinc is when hot, sulphide-laden fluids spew up through fractures in the ocean floor; these fluids form layered volcanogenic deposits.

The weathering processes can also produce economic concentrations of minerals, for instance, placer gold found in river beds.

Due to the fact that no two orebodies are ever alike, to make a comparison among mines is much too risky. Just because the ore on a particular property continues to depth does not necessarily mean that ore on an adjoining property will go along with the same trend.