ROCKS
ROCKS
Rocks
Around 3000 different minerals are found
on Earth, however they are not found in
pure form they are found in rocks.
A rock is a solid, natural material made up
of one or more minerals.
3 Types of Rocks
1. Igneous: form
where hot,
melted minerals
cool and
harden. Can
form above or
below surface
2. Sedimentary Rocks: form when bits of
other rocks and the remains of living
things are cemented together.
Can form under bodies of water or on
Earth’s surface.
3. Metamorphic rocks always form below
Earth’s surface. Formed when heat,
pressure or chemical reactions change
igneous or sedimentary rocks
Igneous Rocks
Deep below Earth’s surface, temperatures
are o hot that they can melt minerals
into magma.
As this magma rises and cools it hardens
creating igneous rocks.
• Igneous rocks that form under ground
are called intrusive rocks.
Many intrusive rocks have large crystals
and course grained texture.
granite
Extrusive: magma that reaches Earth’s
surface is called lava, when it hardens
extrusive rocks are formed.
Small crystals with fine grained textures
Sedimentary Rocks
How do they form?
Sediment is solid material like soil,
pebbles and organic matter that are
carried by air, water, or ice, and settle
out.
How they are formed?
They usually settle at bottom and through
weight of other materials cement together.
75% of Earth’s rocks are Sedimentary
Types of Sedimentary Rocks
1. Clastic: made mainly from fragments of
other rocks(most common sedimentary
rock)
2. Chemical: form from chemicals
dissolved in water(leave behind salt
when water evaporates)
3. Organic: form from remains of living
things
Metamorphic
Formed from heat and pressure, 2 types
1. Foliated: minerals have been
rearranged into visable bands
2. Nonfoliated: don’t show bands
ROCK CYCLE
Series of natural changes that cause one
type of rock to become another type of
rock.