MINERALS AND ROCKS
THE TREASURES OF OUR EARTH!
REVIEW THIS POWERPOINT OFTEN—
IT IS EVERYTHING
YOU NEED TO KNOW!
MINERAL:
A. Naturally occurring
B. Inorganic, Solid
C. Crystalline structure
D. Definite chemical and
physical properties
E. Definite molecular structure
(internal arrangement of atoms)
Minerals are identified based
on their physical properties
1. Color
• Most visible property, but
least reliable.
• Many minerals have the
same color and some have
more than one color.
2. Streak
• Color of a mineral in its powder form
3. Luster
• The way in which light is
reflected from the surface
a. Metallic - shines like
polished metals, rust, heavy
b. Nonmetallic - no
metallic luster
1) glassy, clear
2) pearly, white
3) greasy
4) dull
5) earthy
nonmetallic
metallic
4. Hardness
a. the resistance of a
mineral is compared to
glass by scratching it
against a glass plate (5.5)
b. hardness of a mineral is
determined by Moh's Scale
of Hardness (1 – 10)
5. Cleavage
The tendency of a mineral to split along
flat, even surfaces.
Fracture -Uneven breakage of a
mineral.
(minerals that do not have cleavage
have this!)
Other Properties:
a. Magnetic
b. React with dilute
hydrochloric acid by
effervescing bubbles
c. Taste (salty)
d. Fluorescence
e. Double refraction
f. Radioactive
Minerals Relationship to Rocks:
• Minerals form rocks.
• Most rocks are composed of one or more
minerals
• Monominerallic - composed of one mineral
• Polyminerallic - composed of more than one
mineral
• 10 - 15 minerals form most all of the rocks on
Earth, they are called rock-forming minerals.
Silicates minerals (SiO4)– two
minerals combine to form a compound.
• When they combine they create a
structure called the Silicon-Oxygen
Tetrahedron
3 Rock Types:
Igneous
Crystals
Sedimentary
Metamorphic
Recrystallized
crystals
Sediments
Rocks are classified based on their: Origin
In other words, what environment did they form in???
Igneous Rocks
Formed by cooling and solidification of
lava or magma.
Lava: extrusive
Magma: intrusive
Igneous rocks
Felsic
(Light colored)
Course
Fine
Grained Grained
Glassy
Mafic
(Dark colored)
Course
Fine
Grained Grained
Glassy
A. Igneous Rocks
Intrusive- cools and solidifies from magma
(beneath Earth’s surface), making larger
crystals due to slow cooling.
Granite (coarse crystal texture)
Extrusive – cools and solidifies from lava
(at or near Earth’s surface), making smaller
crystals due to faster cooling.
Obsidian (glassy texture)
Pumice (glassy texture
with vesicles)
Igneous Rock Characteristics
Felsic- forms light-colored rocks that are
high in Al, low density.
Mafic- forms dark-colored rocks that are
high in Mg and Fe, high density.
Vesicular- gas bubbles or air pockets.
Cooling Time Graph
(the longer it takes to cool, the bigger the crystals!)
As time increases, crystal size increases.
IGNEOUS ROCKS
Grain Size
Crystal size
Description
Igneous rocks have
“Intergrown Crystals” – crystals
that form as the rock forms.
Intergrown
Crystals
Not Intergrown
Crystals
Outside the volcano: Extrusive
(lava)
Inside the Earth: Intrusive
(magma)
Where the rock formed
Air Bubbles in the rock?
Yes= Vesicular
No Air
Bubbles?
No = Non-vesicular
Color
Dark
Light
Darkest
Lightest
Density
Low Density
High Density
What Minerals Are in the Rocks?
First, identify the rock, then go straight down the column for the minerals.
This is the amount of Potassium Feldspar in the rock.
This is the amount of Quartz in the rock.
This is the amount of Plagioclase Feldspar in the rock.
Use tick marks on a scrap paper to measure the percentage.
Potassium Feldspar 25%
Quartz 40%
Practice
Name a light-colored, fine-grained
rock with no bubbles.
Name a coarse-grained, dense rock.
Name a very light-colored, glassy,
extrusive rock with bubbles.
Metamorphic Rocks
• Form from metamorphism (change) that
is caused by heat and pressure.
• Usually form deep in the Earth's crust
• Causes a change in the rocks
1. makes the rock more dense
2. separates the rock into layers (banding)
• Metamorphic rocks have been
changed from a pre-existing rock.
• Caused by extreme heat and/or
pressure. (regional)
• Happens over wide “regions.”
• Caused by contact with extreme heat
from a nearby volcano (contact).
• Occurs when the rock is in close
contact with volcanic heat.
Types of Metamorphic Rocks:
1. Contact Metamorphic - Rocks that form
from being close to a heat source (magma)
2. Regional Metamorphic
a. caused mainly by pressure
b. usually cover large areas
c. form during tectonic activity
d. most metamorphic rocks are
formed from regional metamorphism
Metamorphism happens where lava or magma touches other rocks. What
will this limestone rock metamorphose into?
Classification of Metamorphic Rocks
Non-foliated - no visible layers (distorted crystals)
Marble
Foliated Metamorphic Rock – mineral alignment
a. visible layers in the rock
b. form from extreme pressure which
flattens the minerals into layers
c. different mineral densities may
produce alternating light and dark bands of
minerals (banding)
A “GNEISS” ROCK 
Sedimentary Rocks:
Rocks formed from sediments
on Earth’s surface.
Sedimentary Rocks form from sediments
that go through cementation & compaction
EXAMPLES OF SEDIMENT
SIZE FROM LARGEST TO
SMALLEST
Three main types
1. Clastic - made from other existing
rock fragments. Clastic rocks are
identified by the size of the fragments.
2. Chemical - form from minerals once
dissolved in water.
3. Organic - formed from once living
organisms.
Features of Sedimentary Rocks:
Stratification - layering of rocks
caused by different types of
sediments being deposited
Fossils – only found in Sedimentary
Rocks. These are the imprints left by
a once-living organism.
Key Features of Sedimentary Rock
1. Made from sediments or rock
material that has been broken
down in some way.
2. Sedimentary rocks are usually
formed under water.
3. Often layered.
4. Are the only rocks that contain
fossils!
5.Clastic (fragmental) –made by
compaction and cementation of
sediments.
• See Earth Science References
Tables
Mixed
Conglomerate Rock has
rounded fragments
Rocks become rounded when they are exposed to water over long
periods of time, such as rocks formed at the bottom of a river bed.
Breccia Rock has angular
fragments
Chemically formed rocks:
Evaporites
1. Formed when water carrying minerals
evaporates and leaves the minerals
behind.
2. Are identified by the minerals present
(such as halite forms Rock Salt)
• See Earth Science Reference Tables
• Bioclastic• bio= life
• clastic= fragments
• Made from accumulated shells
(limestone) or plants (coal)
• See Earth Science Reference
Tables
Formation of
Coal
The Rock Cycle
Any rock can change into another type of rock!
EARTH SCIENCE REFERENCE TABLES CHART – PAGE 6
Earth Science Rocks!!!
FOR YOUR TEST:
*Know the rock & minerals vocab
*Know the ESRT charts
*Practice Castle Learning
questions!