NDA2017General AbilityGeneral StudiesActual
Which one of the following is not an igneous rock?
Options
- AGabbro
- BGranite
- CDolomite
- DBasalt
Correct answer
C. Dolomite
Step-by-step solution
Igneous rocks form from when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are divided into two groups, intrusive or extrusive, depending upon where the molten rock solidifies. Examples of intrusive igneous rocks are diorite, gabbro, granite, pegmatite, and peridotite. Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals.