Download Mineral

Unit V: Minerals, Rocks &
Resources
What is a mineral?

Mineral: a naturally occurring, inorganic
crystalline structure with a definite
chemical composition and specific
physical properties
Meaning that minerals:




are not man made
were never alive
are made of small, crystals (regularly shaped
solids)
are identifiable by their physical properties
**There are over 2000 minerals on Earth—but 12
minerals make up 90% of the crust (which are
made up of just a few elements)
Physical Properties of Minerals

Color: this is the most obvious property of
all minerals; but you should never rely on
color alone because color varies due to
impurities
Quartz
• Luster: how a mineral reflects light (shine)
Metallic
Looks like
Metal
vs.
Nonmetallic
Dull,
earthy,
Waxy,
glassy

Streak: the color of the mineral’s powder
when rubbed on a streak plate (a piece of
unglazed porcelain tile)
**does not have to be the same color as the
mineral

Hardness: the resistance of a mineral to
being scratched
**the hardness is based on a number
between 1 and 10—with 1 being the
softest (talc) and 10 being the hardest
(diamond)

a higher number can scratch a lower
number (we use glass as our test)

Cleavage or Fracture: how a mineral
breaks

Cleavage: when a mineral breaks into shapes
or has FLAT, SMOOTH surfaces

Fracture: breaks unevenly in rough and
jagged pieces (there is no shape or
pattern)

Density: how much matter is in a certain
amount of space (meaning a mineral may
look heavier or lighter than it actually is)
Very heavy
for its size = high
density

Chemical Properties: properties that not
all minerals have (taste, smell, acid fizz)
Acid Fizz
Salty Taste
“Rotten Egg
Smell”
What are minerals made out of?

Elements (either on their own or bonded
into compounds)
Sulfur (Element)
Halite (NaCl)
Why do minerals made from the same
elements exhibit different properties?
**because of the ATOMIC ARRANGEMENT!!
Carbon Atoms (Diamond)
Carbon Atoms (Graphite)

Silicate Minerals: combination of oxygen
and silicon—forms a Tetrahedron
Structure
(4) Oxygen
Silicon in center
**90% of all
minerals—
most common
What is a Rock?

a combination of one or more minerals (3
types: Igneous, Metamorphic, Sedimentary)
1.
Igneous Rocks: cooling and
crystallization (solidification) of molten
(liquid) rock
→
molten rock can either be magma—below
the surface, or lava—above the surface
Two Igneous Rock Forming Environments
1.
Extrusive (external): started out as
molten lava and cooled on the surface
(cools fast)
2.
Intrusive (internal): started out as
magma and cooled within the crust
(cools slow)
How are igneous rocks classified?
1.
Texture: the size of the mineral crystals
**Because of different rates of cooling,
igneous rocks exhibit different textures

Slow Cooling – magma cools in an
intrusive environment which results in a
rock with large crystals (coarse texture)
Large Crystals

Fast Cooling – lava cools in an extrusive
environment which results in a rock with
small crystals (fine texture)
Small Crystals
2.
Color: determined by the minerals the
igneous rock is composed of

Felsic: light colored igneous rocks with a
composition high in feldspars and silica

Mafic: dark colored igneous rocks with a
composition high in magnesium and iron
2.
Sedimentary Rocks: “Bits and pieces” of
rocks cemented together or they are
chemically created
Pieces of rocks
Chemical Reaction
Three Types of Sedimentary Rocks
1.
Clastic: many sediments (grains)
compressed and cemented together in
horizontal layers (inorganic)
**classified on the basis of grain size
Fine—can’t see (clay)
Medium—can see (sand)
Coarse—can see (pebbles)
Shale
Sandstone
Conglomerate
2.
Chemical (crystalline): evaporation of
water leaves a solid material behind
(evaporites) or by precipitation (settling) of
materials from seawater (precipitates)—
chemical reaction
Rock Gypsum (chemical)
Rock Salt (evaporation)
3.
Organic (Bioclastic): deposition and
compression of plant and animal remains
**sedimentary rocks are the only rocks that
contain fossils (remains of prehistoric
life)… but not all sedimentary rocks
contain fossils
3.
Metamorphic Rocks: changing (recrystallization) of rock because of intense
heat and/or pressure
***The rock that changes can be Igneous,
Sedimentary or other Metamorphic Rock

There is NO MELTING of the existing rock!
What happens if a
rock melts?
Igneous
Two types of metamorphism:
1.
Contact Metamorphism: occurs where
lava / magma comes in contact with rocks
and burns them—small area (high heat)
2.
Regional Metamorphism: occurs deep
under the ground (miles)—large area
(high heat & high pressure)
Two Classifications of Meta Rocks:
1.
Foliated: the mineral crystals are
arranged in layers or bands (can be
distorted—wavy)—Heat & Pressure
2.
Non-foliated- rocks are not banded
(heat and / or pressure)
Inferences we can make by looking at rocks:
Marine Fossils
Sedimentary / Ocean
Glassy
Igneous / cooled fast
Where do you find the three types of rocks?
1.
Sedimentary rocks form a thin layer over
the surface (at most 1 mile)
2.
Igneous: makes up the crust (also by
volcanoes)
Granite
Basalt
3.
Metamorphic: scattered (in / near
mountains, volcanoes, plate boundaries)

**Intrusive igneous and metamorphic
rocks are exposed due to millions of years
of weathering (breaking down) & erosion
(washing away)
Rock Cycle
**model that shows
how rocks change
Natural Resources

Natural Resources: substances that
come from the earth (rocks, minerals,
fuels, trees) that have value to us ($)
Two Types of Resources
1.
Renewable: resources that can be
replaced after they are used (trees)
2.
Non-renewable: resources that once
they are gone, they can never be
replaced—limited supply (Fossil Fuels:
coal, oil, natural gas—all once living)

Alternative Energy Sources: makes use
of renewable fuel sources (solar, wind…)