Download Minerals

Rock Cycle
Plate tectonics recycles the earth’s
crust by destroying crust material along
convergent plate boundaries and
forming new crust along divergent
boundaries.
We call this recycling of material the
ROCK CYCLE.
Rocks are formed by minerals. The
diagram shows how atoms, elements,
minerals and rocks are connected.
combine to
form
combine to
form
atoms
elements
SiO2
minerals
combine to
form
minerals
+ minerals
rocks
Minerals
Minerals are naturally
occurring, inorganic
solids. Some common
minerals are quartz,
mica, feldspar, diamond,
gypsum, talc and calcite.
Diamond
Quartz
Mica
Minerals have a definite
chemical structure which
gives each mineral a set of
unique properties. The
unique properties are used
to identify minerals.
*Color
The color of the mineral.
Term to Describe
–Description of color
Luster
How light is reflected off the mineral
Term to describe:
–Metallic
–Non-metallic
Hardness
The resistance of a mineral to scratching. Scale
of 1 - 10
-Use Moh’s Hardness Scale or Field Hardness to
describe.
The Mohs hardness of a mineral is determined
by observing whether its surface is scratched
by a substance of known or defined hardness.
• Moh’s Scale WS
Streak
The color of a mineral’s powder.
Term to describe
–Individual Colors
Cleavage
Tendency of the mineral to break along
smooth surfaces.
Term to Describe
–Cleavage
Fracture
Minerals that do not have cleavage.
Term to Describe
–Fracture
Crystal form
External expression of a
mineral’s arrangement
of atoms.
Term to Describe
–Crystals
–No Crystals
• Specific Gravity
Weight of mineral compared to
weight of equal volume of
water
Term to Describe
–Heavy or Not heavy
Geologists
classify
minerals into
groups
based on
their
chemical
composition.
The table
shows the
mineral
groups.
Major Mineral Groups
Mineral
Groups
Silicates
Elements
An element + SiO
Carbonates An element + (CO3)
Oxides
An element + O
Sulfates
An element + SO4
Sulfides
An element + S
Halides
NaCl, CaF2, KCl
(*group 1 + group 7 or
group 2 + group 6)
Rocks
Minerals are the building blocks
for rocks.
Most rocks are composed of
more than one mineral. The
minerals within a rock occur
together as a mixture, so they
keep their own properties and
can be seen separately.
Granite is a mixture of the minerals quartz,
feldspar and mica. Each of the minerals in
granite can be seen with the eye and each has
its own distinct color and properties.
Every rock contains clues about its origin. Rocks
are divided into types based on the way they
formed.
Igneous Rocks
Remember that new crust material forms
from molten material beneath the surface
(magma). When magma reaches the
surface it is called lava.
When lava or magma cools and hardens, it forms
igneous rock.
The term igneous means “from fire”, so the term
describes how igneous rock forms.
Magma that cools
and hardens
inside the earth
forms large
crystals within
the rock because
it cools slowly.
These are called
intrusive
igneous rocks.
Lava that cools and
hardens on the
surface of the
earth forms
extrusive igneous
rock. Lava at the
surface forms
smaller crystals
since it cools
faster. These are
called extrusive
igneous rocks.
Metamorphic Rock
Metamorphic means “change form”.
Existing rocks that undergo great heat and
pressure change size, shape, texture and even
mineral content due to chemical reactions.
Force from pressure
can cause the rock to
warm, bend and fold.
The resulting
metamorphic rock will
have a banded
appearance with
flattened crystals.
This is called
foliation.
Not all metamorphic rocks are foliated. Nonfoliated
metamorphic rock does not have the banded appearance.
Sedimentary Rocks
Over time, rocks are continually broken down into
smaller pieces. The breaking down of rock at
the earth’s surface is called weathering. The
pieces or particles of rock are called sediment.
Sediment is transported from one place to
another by gravity, wind, water, and ice.
Moving sediment from one place to another is
called either erosion or mass wasting.
Eventually, sediment is deposited into lakes,
river valleys and oceans.
Sediment may eventually be converted
into rock. Rock formed from sediment
is called sedimentary rock.
There are two main ways that sediment
can become sedimentary rock. One
way is by compaction. Compacted
sedimentary rock forms when the
weight of overlying sediment presses
the bottom sediments together over
time.
The second method is
called cementation.
Sediment in water
can be cemented
together by materials
carried in the water.
The material
precipitates onto the
sediment and over
time, glues the
particles together.
Sedimentary rocks are classified
into 3 types: clastic, chemical
and organic.
Clastic sedimentary rocks are formed by
the cementing and compacting of
sediments.
Chemical sedimentary rocks are formed
when a body of water evaporates and
leaves behind minerals that were
dissolved in the water.
Organic sedimentary rocks form from
material left behind by decaying
plants or organisms.
Rocks are continuously changed from one type of rock to another.
• Crayon rock cycle