Question

How do minerals occur? Explain with examples.

Answer 1

Geologists define a mineral as a naturally occurring, homogenous substance with a defined internal structure. Due to physical and chemical conditions during formation, minerals have unique qualities such as colour, hardness, and density, and they are classified based on these qualities.

Minerals generally occur in these forms:

1. Minerals are found in igneous and metamorphic rocks' cracks, fissures, faults, and joints. Veins are small occurrences, while lodes are massive formations caused by upward mineral migration. They yield significant amounts of metallic minerals.
2. Minerals are found in sedimentary rocks in layers due to deposition and accumulation. Heat and pressure cause the formation of coal and some iron ores. Evaporation produces sodium salt, gypsum, and potash salt, especially in arid areas.
3. Some minerals are formed through the decomposition of surface materials, which results in a residual mass that contains ores. This process is illustrated by bauxite.
4. Placer deposits are natural deposits of some minerals found in valley sands and at the base of hills. They are things like gold, silver, tin, and platinum that don't break down in water.
5. Despite their abundance, most of the minerals in ocean waters are too dispersed for economic use. Magnesium, bromine, and common salt are derived from them, while manganese nodules are discovered in ocean sediments.
6. India has abundant but unevenly dispersed mineral resources. Coal, as well as metallic and non-metallic minerals, are found in peninsular rocks. Petroleum can be found in the sedimentary rocks of Gujarat and Assam, while non-ferrous minerals are found in Rajasthan. Geological variations prevent profitable minerals from being found in the alluvial plains of North India.