MINERALS AND ROCKS
THE TREASURES OF OUR EARTH!
REVIEW THIS POWERPOINT OFTEN —
IT IS EVERYTHING
YOU NEED TO KNOW!

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 (SiO
4
) – two minerals combine to form a compound.
• When they combine they create a structure called the Silicon-Oxygen
Tetrahedron

3 Rock Types:
Igneous Sedimentary
Metamorphic
Crystals
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
(Lite colored)
Mafic
(Dark colored)
Course
Grained
Fine
Grained
Glassey Course
Grained
Fine
Grained
Glassey

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

Crystal size
Grain 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
Light Dark

Low Density
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. size and shape
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).

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)
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 densities may produce alternating light and dark bands (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 pre-existing rocks, fragmental. 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

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

FOR YOUR TEST:
Know the rock & minerals vocab
Know the ESRT charts
Practice Castle Learning questions!