Minerals and Energy Resources Test - 3

Geologists define mineral as a “homogenous, naturally occurring substance with a definable internal structure.” Minerals are found in varied forms in nature, ranging from the hardest diamond to the softest talc.Rocks are combinations of homogeneous substances called minerals.

Rocks are combinations of homogenous substances called minerals. Some rocks, for instance limestone, consist of a single mineral only, but majority of the rock consist of several minerals in varying proportions.Over 2000 minerals have been identified,but only a few are abundantly found in most of the rocks.

A particular mineral that will be formed from a certain combination of elements depends upon the physical and chemical conditions under which the material forms. This, in turn, results in a wide range of colours, hardness, crystal forms, lustre and density that a particular mineral possesses. Geologists use these properties to classify the minerals.The basic chemical materials may be the same, but as the pressure and temperature change, the actual minerals will change too.

Geographers study minerals as part of the earth’s crust for a better understanding of landforms. The distribution of mineral resources and associated economic activities are of interest to geographers. A geologist, however, is interested in the formation of minerals, their age and physical and chemical composition.Geographers also study phenomena above the ground and how the features of the planet - ranging from climate to landforms like mountains - affect humanity.

Minerals are usually found in “ores”. The term ore is used to describe an accumulation of any mineral mixed with other elements.

In igneous and metamorphic rocks, minerals may occur in the cracks, crevices, faults or joints. The smaller occurrences are called veins and the larger are called lodes.

In igneous and metamorphic rocks minerals may occur in the cracks, crevices, faults or joints. The smaller occurrences are called veins and the larger are called lodes.Metallic minerals like tin,copper,zinc and lead etc are obtained from veins and lodes.

In sedimentary rocks a number of minerals occur in beds or layers. They have been formed as a result of deposition, accumulation and concentration in horizontal strata.Sedimentary minerals include gyspum,potash salt and sodium salt.

Certain minerals may occur as alluvial deposits in sands of valley floors and the base of hills. These deposits are called ‘placer deposits’ and generally contain minerals, which are not corroded by water. Gold, silver, tin and platinum are most important among such minerals.

The decomposition of surface rocks, and the removal of soluble constituents, leaving a residual mass of weathered material containing ores. Bauxite is formed this way.