IGNEOUS ROCKS

Metamorphic rocks have been subjected to tremendous heat and/or pressure, causing them to change into another type of rock. They are usually resistant to weathering and erosion and are therefore very hard-wearing.

(1) Cementation is a process that leads to sedimentary rocks. (2) When heat is applied to a rock and it melts, it may form a metamorphic rock. (3) A sedimentary rock in the future may change into another type of sedimentary rock. (4) Solidification is always needed to form an igneous rock.

Extrusive, or volcanic, igneous rocks are formed when molten hot material cools and solidifies. There are three main types of rocks: sedimentary, igneous, and metamorphic. Each of these rocks are formed by physical changes—such as melting, cooling, eroding, compacting, or deforming—that are part of the rock cycle.

Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors.

sedimentary rocks

Explanation: Option ( 2 ), Besalt is the best example of metamorphic rock. The metamorphic Basalt is dark-coloured, fine-grained, igneous type of rock analysed primarily of plagioclase and pyroxene types of minerals.

There are three kinds of rock: igneous, sedimentary, and metamorphic. Igneous rocks form when molten rock (magma or lava) cools and solidifies. Sedimentary rocks originate when particles settle out of water or air, or by precipitation of minerals from water. They accumulate in layers.

Primary mineral, in an igneous rock, any mineral that formed during the original solidification (crystallization) of the rock. In contrast to primary minerals are secondary minerals, which form at a later time through processes such as weathering and hydrothermal alteration.

The fundamental distinction between primary and secondary processes is that secondary mechanisms can only break existing rocks, whereas primary mechanisms are capable of both creating and degrading rocks.

Rocks composed of particles derived from the erosion or weathering of preexisting rocks, such as residual, chemical, or organic rocks formed of detrital, precipitated, or organically accumulated materials; specif., clastic sedimentary rocks.