MINERALS AND ROCKS

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MINERALS AND ROCKS

• THE TREASURES OF OUR EARTH!
• REVIEW THIS POWERPOINT OFTENIT IS EVERYTHING
• YOU NEED TO KNOW!

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MINERAL

• A. Naturally occurring
• B. Inorganic, Solid
• C. Crystalline structure
• D. Definite chemical and
• physical properties
• E. Definite molecular structure
• (internal arrangement of atoms)

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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.

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2. Streak

• Color of a mineral in its powder form

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3. Luster
nonmetallic

• 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

metallic
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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)

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• 5. Cleavage
• The tendency of a mineral to split along flat,
  even surfaces.

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Fracture -Uneven breakage of a mineral. (minerals
that do not have cleavage have this!)
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Other Properties

• a. Magnetic
• b. React with dilute
• hydrochloric acid by
• effervescing bubbles
• c. Taste (salty)
• d. Fluorescence
• e. Double refraction
• f. Radioactive

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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.

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Silicates minerals (SiO4) two minerals combine
to form a compound.

• When they combine they create a structure called
  the Silicon-Oxygen Tetrahedron

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3 Rock Types
Metamorphic

• Igneous

Sedimentary
Recrystallized crystals
Crystals
Sediments
Rocks are classified based on their Origin In
other words, what environment did they form in???
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Igneous Rocks Formed by cooling and
solidification of lava or magma. Lava
extrusive Magma intrusive
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A. Igneous Rocks

• Intrusive- cools and solidifies from magma
  (beneath Earths surface), making larger
  crystals due to slow cooling.

Granite (coarse crystal texture)
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Extrusive cools and solidifies from lava (at or
near Earths surface), making smaller crystals
due to faster cooling.
Obsidian (glassy texture)
Pumice (glassy texture with vesicles)
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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.

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Cooling Time Graph(the longer it takes to cool,
the bigger the crystals!)
As time increases, crystal size increases.
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IGNEOUS ROCKS
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Crystal size
Grain Size
Description
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Igneous rocks have Intergrown Crystals
crystals that form as the rock forms.
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IntergrownCrystals
Not Intergrown Crystals
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Where the rock formed
Inside the Earth Intrusive
(magma)
Outside the volcano Extrusive
(lava)
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Air Bubbles in the rock?
Yes Vesicular
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No Air Bubbles?
No Non-vesicular
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Color
Light
Dark
Lightest
Darkest
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Density
Low Density
High Density
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What Minerals Are in the Rocks?
First, identify the rock, then go straight down
the column for the minerals.
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This is the amount of Potassium Feldspar in the
rock.
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This is the amount of Quartz in the rock.
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This is the amount of Plagioclase Feldspar in the
rock.
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Use tick marks on a scrap paper to measure the
percentage.
Potassium Feldspar 25
Quartz 40
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Practice
Name a light-colored, fine-grained rock with no
bubbles.
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Name a coarse-grained, dense rock.
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Name a very light-colored, glassy, extrusive
rock with bubbles.
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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)

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• 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.

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• 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

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Metamorphism happens where lava or magma touches
other rocks. What will this limestone rock
metamorphose into?
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• Classification of Metamorphic Rocks
• Non-foliated - no visible layers (distorted
  crystals)

Marble
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• 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 ?
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Sedimentary RocksRocks formed from sediments on
Earths surface.
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• Sedimentary Rocks form from sediments that go
  through cementation compaction

EXAMPLES OF SEDIMENT SIZE FROM LARGEST TO SMALLEST
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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.
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Features of Sedimentary Rocks

• Stratification - layering of rocks caused by
  different types of sediments being deposited

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• Fossils only found in Sedimentary Rocks. These
  are the imprints left by a once-living organism.

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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!

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• 5.Clastic (fragmental) made by compaction and
  cementation of sediments.
• See Earth Science References Tables

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Mixed
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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.
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Breccia Rock has angular fragments
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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

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• Bioclastic-
• bio life
• clastic fragments
• Made from accumulated shells (limestone) or
  plants (coal)
• See Earth Science Reference Tables

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Formation of Coal
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The Rock Cycle

• Any rock can change into another type of rock!

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EARTH SCIENCE REFERENCE TABLES CHART PAGE 6
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Earth Science Rocks!!! FOR YOUR TESTKnow the
rock minerals vocabKnow the ESRT
chartsPractice Castle Learning questions!