Mode of Occurrence of Minerals

Minerals are important for various industries and economic activities and are found in ores, which are accumulations of minerals mixed with other elements. The mode of occurrence of minerals determines their extraction feasibility and cost, making it essential to comprehend the main types of mineral formations.

Igneous and Metamorphic Rocks

• Minerals may occur in igneous and metamorphic rocks within cracks, crevices, faults, or joints, forming veins or lodes.
• These formations result from minerals in liquid or gaseous forms being forced upward through cavities, cooling, and solidifying as they rise.
• Major metallic minerals like tin, copper, zinc, and lead are obtained from veins and lodes.

Sedimentary Rocks

• In sedimentary rocks, minerals occur in beds or layers due to deposition, accumulation, and concentration in horizontal strata.
• Coal and some forms of iron ore are concentrated under heat and pressure over long period of time.
• Sedimentary minerals like gypsum, potash salt, and sodium salt form through evaporation, particularly in arid regions.

Weathering and Residual Mass

• Minerals may form through the decomposition of surface rocks, with soluble constituents removed, leaving a residual mass containing ores.
• Bauxite is an example of a mineral formed through this process.

Placer Deposits

• Certain minerals occur as alluvial deposits in sands of valley floors and base hills, known as placer deposits.
• These deposits contains minerals resistant to water corrosion and include gold, silver, tin, and platinum.

Ocean Waters

• While ocean waters contain vast mineral quantities, most are too widely dispersed to be economically significant.
• Common salt, magnesium, and bromine are derived from ocean waters, with ocean beds rich in manganese nodules.

Minerals occur in various modes depending on geological processes. They can be found as deposits within rocks, such as veins or layers. Some minerals form through precipitation from solutions, like evaporite deposits in salt lakes. Others are found in alluvial deposits, transported by water and deposited in riverbeds or deltas. Minerals can also occur as nodules or concretions within sedimentary rocks. India’s mineral distribution varies, with peninsular rocks containing coal and metallic minerals, while sedimentary rocks in Gujarat and Assam contain petroleum deposits.

In this article, we will look into the mode of occurrence of minerals and the factors that influence their distribution. It is an important concept of Class 10 Geography. Students can go through this article to get comprehensive notes on “Mode of Occurrence of Minerals”.