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The Forming Of Rocks And
Created by Jennifer Taveras
What Are Rocks And Minerals
Rock is our world. The
planet Earth is,
essentially, just one big
interesting rock,
sometimes called "the
third rock from the sun."
The multi-faceted rock
we live on supports life
in many ways. The
deep oceans, the vast
deserts, and the high
mountains, are just a
few of the ways rock
emerges and supports
Types Of Rock’s
• Sedimentary
Sedimentary rocks are
formed from particles
of sand, shells,
pebbles, and other
fragments of material.
Together, all these
particles are called
sediment. Gradually,
the sediment
accumulates in layers
and over a long period
of time hardens into
rock. Generally,
sedimentary rock is
fairly soft and may
break apart or
crumble easily.
How Many Types Of Rocks Are
This question has both a simple and a complicated answer. There are three basic types of rocks:
igneous, sedimentary, and metamorphic. Within each of these groups, however, there are
hundreds of subdivisions based on the types and amounts of minerals the rock contains and/or
the rock’s texture.
These three basic rock classes are defined by how the rock formed.
Igneous rocks such as granite and basalt form when molten rock cools inside the earth or during
volcanic eruptions, respectively. Sedimentary rocks are the product of physical and chemical
processes at the earth’s surface that cause the breakdown of other rocks into small pieces known
as sediments. The small pieces of rock then get “glued” together to form “clastic” sedimentary
rocks, such as sandstone and shale. Limestone and gypsum are two examples of “chemical”
sedimentary rocks that form as a result of chemical reactions in water.
Metamorphic rocks are igneous or sedimentary rocks that have been changed because of
exposure to high temperatures and/or pressures. When rocks are heated or squeezed, the original
minerals in the rock may change into other minerals or reorient themselves, altering the rock’s
chemical composition and texture. Common examples are marble (metamorphosed limestone)
and slate (metamorphosed shale).
Most of the rocks we see on the earth’s surface are sedimentary. Igneous rocks are most common
inside the earth. Metamorphic rocks are found in mountains and other places where forces due to
movements of the earth’s plates cause rocks to deform, as well as inside the earth, where rocks
are subjected to pressure from the overlying rocks and heat from both radioactive decay and the
earth’s core.
What Is The Different About Rocks
And Minerals?
• A mineral is a naturally-occurring inorganic (there are
some exceptions to this) crystalline solid (though
mercury is regarded as a mineral) with a specific
chemical composition and a characteristic internal
regular geometric arrangement of atoms, sometimes
expressed as natural crystal faces.
• A rock is an aggregate of one (such as quartzite) or more
(such as granite) mineral particles formed through either
crystallisation of molten magma (igneous rocks), settling
of particles (sedimentary rocks), or reheating and
pressure applied to pre-existing rocks (metamorphic
rocks), with no set chemical composition or atomic
structure. Rocks are minerals but not all minerals are
The Forming Of And Minerals
• A rock is defined as an aggregate of mineral grains,
which means that rocks are a bunch of mineral grains all
stuck together. The mineral grains may be large enough
to be seen with the naked eye (phaneritic) or
microscopic (aphanitic).
• The three types of rocks are igneous, sedimentary and
metamorphic. Igneous rocks form when molten rock, or
magma, cools and hardens. Sedimentary rocks result
from erosion of any rock type, followed by depositing the
resulting sediment into a natural basin, and finally
cementing the sediment into stone. Metamorphic rocks
form when any rock is subjected to great heat and
pressure, but not enough heat to melt the rock.
What Are Minerals
• The majority of metals,
chemicals and industrial
products that are now
considered essential to
modern life come from
minerals. Farming and
forestry for instance
depend upon the soil,
which is heavy in
minerals. The most
visible examples of
minerals are stones and
rocks. With notable
exception of mercury.
How Many Types Of Minerals Are There
• At present there are nearly 3000 different
types of named minerals. Their number is
always increasing - in fact, 30 more new
minerals are discovered every year.
What Are Rocks And Minerals For?
– you'll find in Quartz
• Quartz is one of the most common minerals in the
Earth's crust. It is made up of silicon dioxide (SiO2),
otherwise known as silica. White sand is primarily
made from quartz. Click here to find out more.
• Plagioclase feldspar
• Plagioclase is a member of the feldspar mineral
family. Plagioclase feldspars are yet another silicate
that contains considerable sodium or calcium.
Feldspar crystals are stubby prisms, generally white
to gray and a glassy luster. This variety of plagioclase,
called albite, is rich in sodium.