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CHEMISTRY, ROCKS, AND MINERALS
ATOMS:
Are made up of chemical elements.
Each element has a nearly identical atoms.
Atoms have three different particles:
- protons (+) located in center of atom
-electrons (-) located around center of atom
-neutrons (0) located in center of atom
ELEMENT:
Elements have the same # of protons and
electrons
 number of protons = number of electrons
Isotopes of an element have the same number of protons
and electrons, but they have a different number of
neutrons.
Many isotopes are radioactive and emit energy and
ATOMS:
Have energy levels, or shells:
They surround the nucleus (center of atom)
Contain electrons- negatively charged particles
WHY ATOMS BOND
When an atom’s does not contain a full outer
shell, it is likely to form a chemical bond with
one or more atoms.
A compound: consist of two or more
elements that are chemically combined in
specific proportions.
TYPES OF CHEMICAL BONDS
1. Ionic bonds: form between metal and nonmetal
2. Covalent bonds: form between two non-metals.
3. Metallic bonds: form between two metals.
ORGANIC VS. INORGANIC
Organic: Made of Carbon and hydrogen
Normally living organisms or products of living organisms
Inorganic: Made of everything else
Normally non-living or man made
THE ROCK CYCLE
Rocks
 Rocks are any solid mass of mineral or
mineral-like matter occurring naturally
as part of our planet.
 Types of Rocks
1. Igneous rock is formed by the crystallization
of molten magma.
THE ROCK CYCLE
Rocks
 Types of Rocks
2. Sedimentary rock is formed from the
weathered products of preexisting rocks that
have been transported, deposited, compacted,
and cemented.
3. Metamorphic rock is formed by the alteration
of pre-existing rock deep within Earth (but still
in the solid state) by heat, pressure.
THE ROCK CYCLE
The Rock Cycle
 Shows the relationships among the three rock
types (igneous, sedimentary, and
metamorphic)
 Magma is molten material that forms deep
beneath the Earth’s surface.
 Lava is magma that reaches the surface.
 Weathering is a process in which rocks are
broken down by water, air, and living things.
 Sediment is weathered pieces of Earth
elements.
THE ROCK CYCLE
THE ROCK CYCLE
Energy That Drives the Rock Cycle
 Heat from the Earth’s interior are responsible
for forming both igneous rock and
metamorphic rock.
 Weathering and the movement of weathered
materials are surface processes powered by
energy from the sun.
 Surface processes produce sedimentary
rocks.
IGNEOUS ROCKS
Formation of Igneous Rocks
1. Intrusive igneous rocks are formed
when magma hardens beneath Earth’s
surface.
2. Extrusive igneous rocks are formed
when lava hardens.
IGNEOUS ROCKS
Classification of Igneous Rocks
 Igneous rocks can be classified based
on their composition and texture.
1. Texture
• Coarse-grained texture is caused by slow
cooling resulting in larger crystals.
• Fine-grained texture is caused by rapid
cooling resulting in smaller mineral grains.
COURSE-GRAINED IGNEOUS TEXTURE
FINE-GRAINED IGNEOUS TEXTURE
IGNEOUS ROCKS
Classification of Igneous Rocks
1. Texture (continued)
• Glassy texture is caused by very rapid cooling.
• Porphyritic texture is caused by different rates
of cooling resulting in varied sized minerals.
2. Composition
• Granitic composition rocks are made mostly
of light-colored quartz and feldspar.
OBSIDIAN EXHIBITS A GLASSY TEXTURE.
PORPHYRITIC IGNEOUS TEXTURE
3.2 IGNEOUS ROCKS
Classification of Igneous Rocks
2. Composition (continued)
• Basaltic composition rocks are made mostly
of dark-colored silicate minerals and
plagioclase feldspar.
• Andesitic composition rocks are between
granitic light-color minerals and basaltic
composition dark-colored minerals.
• Ultramafic composition rocks are made mostly
from iron and magnesium-rich minerals.
BASALT
CLASSIFICATION OF IGNEOUS ROCKS
SEDIMENTARY ROCKS
Formation of Sedimentary Rocks
 Weathering, Erosion, and Deposition
• Erosion involves the weathering and the
removal of rock.
• Deposition occurs when an agent of
erosion—water, wind, ice, or gravity—loses
energy and drops sediments
SEDIMENTARY ROCKS
Formation of Sedimentary Rocks
 Compaction and Cementation
• Compaction is a process that squeezes, or
compacts, sediments.
• Cementation takes place when dissolved
minerals are deposited in the tiny spaces
among the sediments.
SEDIMENTARY ROCKS
Classification of Sedimentary Rocks
 Two Main Groups
1. Clastic sedimentary rocks are composed
of weathered bits of rocks and minerals.
• Classified by particle size
• Common rocks include
- Shale (most abundant)
- Sandstone
- Conglomerate
SHALE WITH PLANT FOSSILS
CONGLOMERATE
SEDIMENTARY ROCKS
Classification of Sedimentary Rocks
 Two Main Groups
2. Chemical sedimentary rocks form when
dissolved substances separate from water.
• Common rocks include
- limestone—most abundant chemical rock
- microcrystalline quartz known as chert, flint,
jasper, or agate
- evaporites such as rock salt or gypsum
- coal
FOSSILIFEROUS LIMESTONE
CLASSIFICATION OF
SEDIMENTARY ROCKS
METAMORPHIC ROCKS
Formation of Metamorphic Rocks
 Metamorphism means “to change
form.”
 Form at elevated temperatures and
pressures.
 Found a few kilometers below the
Earth’s surface and into the upper
mantle.
METAMORPHIC ROCKS
Formation of Metamorphic Rocks
 Contact metamorphism occurs when
magma moves into rock.
• Occurs near a body of magma
• Changes are driven by a rise in temperature.
3.4 METAMORPHIC ROCKS
Formation of Metamorphic Rocks
 Regional metamorphism
• Directed pressures and high temperatures
occur during mountain building.
3.4 METAMORPHIC ROCKS
Agents of Metamorphism
 Heat
• Provides the energy needed to drive chemical
reactions
 Pressure
• Causes a more compact rock with greater
density
ORIGIN OF PRESSURE IN
METAMORPHISM
3.4 METAMORPHIC ROCKS
Classification of Metamorphic Rocks
 Two main categories
1. Foliated Metamorphic Rock
• Has a banded or layered appearance
2. Nonfoliated Metamorphic Rock
• Does not have a banded texture
CLASSIFICATION OF METAMORPHIC
ROCKS
GNEISS TYPICALLY DISPLAYS A
BANDED APPEARANCE
MARBLE — A NONFOLIATED
METAMORPHIC ROCK
ROCK IMAGES WEBSITE LINK
http://geology.com/rocks/
MINERALS
Mineral: a
naturally
occurring,
inorganic
crystalline material
with a unique
chemical
composition.
http://www.feenixx.com/earthscience/Introduction_to_Minerals_Poster.htm
MINERALS:
Naturally formed- it forms in nature on its own
Orderly crystalline structure
Solid (cannot be liquid or gas)
Has to have a definite chemical composition
Has to have a characteristic crystalline structure
EXAMPLES OF MINERALS:
Glass- can be naturally formed (volcanic glass is called
obsidian)
Ice- is naturally formed, is a solid, has definite chemical
composition
Halite (salt)- naturally formed, is solid, has definite
crystalline structure.
CHARACTERISTICS OF MINERALS
Color
Streak
Luster
Crystal form
Hardness
Cleavage
Fracture
Density
CHARACTERISTIC OF MINERALS- COLOR
Color:
Small amounts of
different elements can
give the same mineral
different colors.
CHARACTERISTIC OF MINERALS- STREAK
Streak: is the color of a mineral in its powered form.
CHARACTERISTIC OF MINERALS- LUSTER
Luster: is used to describe how light is reflected from the
surface of a mineral.
CHARACTERISTIC OF MINERALS- CRYSTAL FORM
Crystal form: is the visible expression of a mineral’s
internal arrangement of atoms.
CHARACTERISTIC OF MINERALS- HARDNESS
Hardness: is a measure
of the resistance of a
mineral to being
scratched.
Mohs scale: consists of
10 minerals arranged
from 10 (hardest) to 1
(softest)
CHARACTERISTIC OF MINERALS- CLEAVAGE
Cleavage: is the tendency of a mineral to cleave, or
break, along flat, even surfaces.
CHARACTERISTIC OF MINERALS- FRACTURE
Minerals that do not show cleavage when broken are said
to fracture.
Fracture: the uneven breakage of a mineral
CHARACTERISTIC OF MINERALS- DENSITY
Density: is a property of all matter that is the ratio of an
object’s mass to its volume.