Igneous rocks are crystalline.
Metamorphic rocks are changed rocks due to exposure to high heat and pressure. Magma is molten rock generally thought to have originated in the asthenosphere in the uppermost mantle. If the minerals are too small to be readily identified by the naked eye, then color is used for the extrusives. Sediment is composed primarily of the weathering products of rocks and minerals, also of organic material that can be transported by wind, water , ice or gravity. Sedimentary grains become rounded by the abrasive action and collisions with the other sediment grains during transportation.