Very Short Question and Answers - Non-Metallic Minerals

Non-metallic minerals are minerals that do not yield metals on smelting and are generally poor conductors of heat and electricity. They are used for their chemical and physical properties rather than for metal content.

The three important non-metallic minerals studied are mica, limestone, and gypsum.

Mica is a flaky, crystalline mineral that splits into thin, flexible sheets. It is heat resistant, a good electrical insulator, chemically inert, and can be transparent to translucent.

Major mica belts are located in Jharkhand (especially Koderma), Bihar (Giridih, Hazaribagh), Rajasthan, Andhra Pradesh (parts of Nellore), and Tamil Nadu.

Mica is mined in sheets or as coarse material. Sheets are trimmed and cut for uses requiring large pieces. Lower-grade mica is ground into powder (ground mica) used as filler or coating.

Mica is used as insulators and dielectrics in electronic equipment, insulating windows in heating devices, and mica washers/spacers in toasters and electrical motors.

Finely ground mica adds shine and sparkle in cosmetics such as lipsticks, eyeshadows, nail polishes, and body powders, creating a glitter effect.

Unregulated mica mining, especially in Jharkhand, has led to social issues including unsafe working conditions and child labour.

Limestone is mainly composed of calcium carbonate (CaCO3).

Limestone deposits are found in Madhya Pradesh, Chhattisgarh, Rajasthan, Andhra Pradesh, Gujarat, Maharashtra, and Karnataka.

Limestone is quarried and crushed to required sizes. Calcination (heating) turns it into quicklime (CaO), and when slaked with water, it forms slaked lime (Ca(OH)2). Ground limestone is also used as filler or flux.

Limestone is the main raw material for cement production. It is mixed with clay and other materials to produce clinker, which is then ground to form Portland cement.

Limestone acts as a flux in blast furnaces, removing impurities by forming slag, thus purifying iron in steel production.

Ground limestone, known as agricultural lime, is used to neutralize acidic soils, improving pH and providing calcium nutrients to crops.

Gypsum is a soft evaporite mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O.

Gypsum is mainly found in Rajasthan (Jodhpur region, including Bap), Gujarat, Haryana, Uttar Pradesh, parts of Jammu & Kashmir, and Madhya Pradesh.

Plaster of Paris is made by partially heating (calcining) gypsum, which removes water molecules. When mixed with water, POP sets quickly and hardens.

Gypsum is used to make plaster of Paris for medical casts and decorative moulding, gypsum boards for walls and ceilings in construction, and as a soil conditioner in agriculture.

Mining of gypsum and limestone can cause land degradation and dust pollution, requiring proper reclamation and environmental management.

Mica is mainly used for electrical insulation, cosmetics, paints, and heat-resistant parts; limestone is essential for cement, steel flux, glass making, agriculture lime, and construction; gypsum is used for plaster of Paris, gypsum boards, cement setting control, and soil conditioning.