What are igneous rocks and it's …

Igneous rocks are defined as types of rocks that are formed when molten rock (rock liquefied by intense heat and pressure) cools to a solid-state.

Lava is molten rock flowing out of fissures or vents at volcanic centers (when cooled they form rocks such as basalt, rhyolite, or obsidian). Pyroclastic deposits are accumulations of fragmented material (e.g. ash, bombs, tuffs, and volcanic breccias) ejected during volcanic eruptions.

Types of Igneous Rock

Following are the two types of igneous rock:

1. Intrusive igneous rock: These rocks crystallize below the earth’s surface resulting in large crystals as the cooling takes place slowly. Diorite, granite, pegmatite are examples of intrusive igneous rocks.
2. Extrusive igneous rock: These rocks erupt onto the surface resulting in small crystals as the cooling takes place quickly. The cooling rate is for a few rocks is so quick that they form an amorphous glass. Basalt, tuff, pumice are examples of extrusive igneous rock.