Rocks: A rock is an aggregate of minerals and it may be mono-minerallic, bi-minerallic or poly-minerallic in composition. Based on their origin, rocks are classified in to three broad divisions- Igneous, sedimentary and metamorphic.
- Igneous rocks are those that have been formed by the consolidation of the hot molten rocky material. eg. Granite, Gabbro, Basalt.
- Sedimentary rocks are secondary rocks. They are derived from the pre-existing rocks by the action of the dynamic agents of the atmosphere and hydrosphere. They result owing to the transportation and accumulation of the disintegrated and decomposed materials in the basins of sedimentation. eg. Sandstone, Limestone.
- Metamorphic rocks are pre-existing rocks that have undergone a change owing to the play of the heat or pressure or owing to the action of chemical agents give rise to metamorphic rocks. eg. Gneiss, Schist, Marble, Quartzite.
Uses: Rocks are mainly used in construction. Those that are capable of taking high polish are employed as decorative stones.
Rocks and minerals:
- Pale Yellow Fluorite:
- Charnockite, Pallavararam, Chennai:
- Stearite Talc, Papparappatti, Salem Dt:
- Hematite, Ambadu Nagar, Gujarat State:
- Grey Babite (Gramliar), Mangarapet, Cuddappa Dt:
- Grey Limestone, Andhra Pradesh:
- Sunstone in Pegmatite, Kiranur, Trichy Dt:
- Cordiorite, Sakkarakottai, Trichy Dt:
- Red Sand Stone, Rajasthan: