Rocks
ROCKS:
Rock is a coherent, naturally occurring solid, consisting of an aggregate of minerals or a mass of glass. To understand this definition we lets take it apart.
Coherent: A rock holds together and it must be broken into separate pieces.
Naturally Occurring: Geologist considers only naturally occurring materials to
be rocks, so bricks and concrete do not consider as rock.
An Aggregate of Mineral OR A Mass of Glass: The vast majority of rocks
consist of an aggregate (a collection) of many crystal minerals.
CLASSIFICATION:
People have developed classification scheme for just about every group of materials on the planet.
Rocks are classified into three types which are:
(I) IGNEOUS ROCKS
(II) SEDIMENTARY ROCKS
(III) METAMORPHIC ROCKS
(I) IGNEOUS ROCKS: Igneous rocks form by the freezing and solidification of molten rock.
(II) SEDIMENTARY ROCKS: Which form either by the cementing together of fragment (grain) broken off pre-existing rocks.
(III) METAMORPHIC ROCKS: When pre-existing rock changes into a new rock under a high pressure and temperature.