Economic Importance of the Rocks:
Rocks are classified into three types. This classification is based on their origin, formation, properties, and composition. The very first type of rock is an igneous rock. Igneous rock is the one, which is extruded from the internal molten mantle in the form of Lava. The molten lava, when exposed to the low temperature on the earth’s crust, cools down and gets harden. The majority of the Igneous Rocks is composed of Felsic and Mafic minerals. Sedimentary rocks are counted as the secondary formed rocks. As the weathered particles of the Igneous rocks are eroded away by means of stream, winds, and process of abrasion carried out by glaciers. The eroded sediments are deposited in the form of layers at low lying areas. The deposition of the sediments continues in the form of layers. Each lower layer is then compressed by the upper layers. The compression causes compaction and solidification of these rocks. These compacted layers are called Sedimentary layers of the rocks. The third type of rock is known as metamorphic rocks. The metamorphic rocks originate from igneous and sedimentary rocks. The igneous and the sedimentary rock go through a process of metamorphism. Metamorphism is a process of extreme heating and pressure. After going through the process of heating and pressure, the sedimentary as well the igneous rocks are converted into the metamorphic rocks. Examples of Metamorphic rocks are Marble, Quartzite, Phylite, Schist, and Gneiss, etc.
- Classification of Rocks
- Igneous rocks and their types
- Sedimentary rocks and their types
- Metamorphic Rocks and their types
All three types of rocks have their individual economic importance.
Economic Importance of the Sedimentary Rocks:
Sedimentary rocks are of great economic importance, as they are a major source of construction material. Most of the sedimentary rocks are found in a layered form, therefore, their natural shape is fit for the masonry work. Limestone is an abundant rock, found almost in every part of the world. Blocks of limestone are used as a constructive material. Chalk is a value-able substance obtained from limestone, which is also used for manufacturing cement and whitewash powder (lime). Limestone is white, and sometimes white with other colors, due to the presence of impurities like Iron Oxide, clay, sand, organic remain, and other minerals. The rocks of limestone are easily soluble in water and acidic rain. It is also pervious to water and other liquids. The water easily penetrates into the pores and cracks of the rock beds, thus making them further hollow. In areas of limestone distinctive landscape is formed, which is known as karst topography. The karst topography results in caves and caverns. Sandstone is another example of sedimentary rocks. Sandstone is used as a building material from ancient times. Many historical buildings like the Tomb of Akbar (Agra), Imperial Mosque Lahore, and Mosque of Wazir khan are purely made up of Sandstone.
Shale is another important sedimentary rock, which has many contributions to economic growth. It is used in the ceramic industry to make bricks, tiles, and pottery. Shale needs crushing into fine grains, before mixing with water to prepare the pottery material. Ground shale is mixed with limestone powder and heated to prepare cement for the construction industry.
Economic Importance of the Igneous Rocks:
Most of the igneous rocks are used as constructing stone, facing stone, and decorative material. Granite is the most abundant igneous rock on the planet. It is a very hard and durable rock, which is cut in the form of blocks and bricks. Pumice is another porous igneous rock, which is used as an abrasive material in cleaning, polishing, and scouring. It is also used as a lightweight precast masonry, insulation, and acoustic tiles, and poured concrete.
Economic Importance of the Metamorphic Rocks:
Metamorphic rock is a tertiary rock, which is evolved from the pre-existed sedimentary and igneous rocks. The sedimentary and igneous rocks go through a process of extreme heat and pressure, known as metamorphism. The process of metamorphism further increases the compaction and strength of the stones. The most common metamorphic rocks are crystalline limestone, slate, Phylite, greywacke, Serpentine, Gneiss, Schist, and Quartzite. All these rocks have great economic importance. For example, Gneiss, Gabro, and Schist are very hard igneous rocks, which are used in concrete aggregate, road surface, railroads, after being crushed into boulders and gravels.
Another important metamorphic rock is slate, which has many uses such as snooker tables, roofing, gravestones, flooring, and garden decorations. Quartzite is a beautiful and lustrous stone, which is used as a decorative material. It is used to construct the outer and interior wall sheathing. Quartzite is also used as a floor sheath. Marble is a metamorphic rock that originates from the layers of limestone. The metamorphic form of the limestone is Marble. Marble is basically white-colored rock, but it can be found in other colors due to the presence of impurities like iron oxide, organic remains, and clay. Marble is used as a construction and decorative material.