Rocks and MineralsUnit 2 Minerals

Why are minerals important?Give us insight to Earth’s history and development

Essential to Industry- Copper, iron, aluminum

Seen in our daily lives- Mica in toothpaste, talc in makeup, hematite in steel, TV needs silica, iron, copper

What is a mineral?A mineral is: naturally occurring, inorganic, solid, that has a definite chemical composition, and a crystal structure.

1. Naturally occurring:a. Minerals- quartz, pyriteb. Not minerals- cement, steel

Minerals

2. Inorganic: NOT formed from living things or the remains of living things.

a. Coal is NOT a mineral because it comes from Plants.b. Amber is NOT a mineral because it comes from Sap.c. Pearls are NOT a mineral because it comes from

Oysters.

Definite Chemical Composition- Pg 16 ESRT

Halite NaCl Sodium Chloride 1 Sodium/ 1 Chlorine

Quartz SiO2 Silicone Dioxide 1 Silicon/ 2 Oxygen

Pyrite FeS2 Iron Sulfide 1 Iron/ 2 Sulfur

Hematite Fe2O3 Iron Oxide 2 Iron/ 3 Oxygen

Magnetite Fe3O4 Iron Oxide 3 Iron/ 4 Oxygen

Definite Chemical Composition- Pg 16 ESRT

Calcite CaCO3 Calcium Carbonate 1 Calcium/ 1 carbon/ 3 oxygen

Graphite C Carbon 1 carbon

Diamond C Carbon 1 carbon

Sulfur S Sulfur 1 sulfur

Minerals4. Solids- have a definite SIZE/VOLUME and a definite SHAPE.

Oil is not a mineral because it is a liquid.

5. Crystal Structure: Atoms arranged in repeating patterns, characteristic geometry of its internal structure of atoms.

Because the atoms are arranged differently.

Diamond Graphite

The following minerals are both made of pure Carbon, why do they look different?

Formation of Minerals1. From cooling of lava/magma

Formation of Minerals2. When water evaporates, dissolved minerals remain behind.

Ex: When a solution (water) is saturated with minerals, minerals will settle out of the solution. “PRECIPITATES.”

Dead Sea

Identifying MineralsIdentifying minerals- minerals can be identified by their physical and chemical properties.

1. Color: a. Some minerals have only one color:

(1) Malachite- green(2) Sulfur- yellow

B. Other minerals have many colors:

(1) Quartz- clear, pink, purple, white, brown(2) Hematite- black, grey, reddish brown, dark red

Color can vary as a result of:

(1) Natural coloring agents: Impurities

(2) Weathering: Exposure to the environment. Ex: air, temperature changes, pollution

-Small amounts of different elements can give the same mineral different colors. Thus, color is not reliable.

StreakStreak- the color of the powder when a mineral is rubbed on a streak plate.

a. Hematite

Streak: Reddish Brown

b. Quartz

Streak: white/colorless

LusterLuster- the way a mineral shines or reflects light from its surface

a) Metallic- shines/reflects light like the surface of a polished metal.

Examples: galena, pyrite, graphite, magnetite

b) Nonmetallic

(1) Pearly- mica(2) Glassy- quartz, halite(3) Dull, earthy- bauxite(4) Waxy- talc(5) Brilliant- diamond

Hardness4. Hardness- a measure of how easily a mineral can be scratched.

a. Softest mineral- TALCb. Hardest mineral- DIAMOND

2.5 Fingernail

3.5 Copper

4.5 Iron Nail

5.5 Glass

6.5 Steel File

7 Streak Plate

Hardness

Now try to answer the questions on page 5 of your note packet.

E. What determines hardness?

Minerals internal structure- the strength of the bonds between the atoms.

Cleavagea. Cleavage- when a mineral splits along smooth flat surfaces

Examples of cleavage:

The mineral mica cleaves in ONE direction.

The mineral galena cleaves in THREE directions.

CleavageWhat determines cleavage?

Internal structure of mineral- types of bonds between atoms.

Cleavage should not be confused with crystal shape. Cleavage is a property of the way a mineral BREAKS, while crystal shape is a property of the way a mineral GROWS. When minerals have plenty of space to grow, they form CRYSTALS.

FractureFracture- when a mineral breaks unevenly into curved or irregular pieces with rough and ridged surfaces.

Examples of Minerals that show fracture:

Sulfur, bauxite, hematite, quartz

Density or HeftA piece of gold has 8 times as much mass as a piece of halite that is the same size.

Chemical/Special PropertiesCALCITE reacts with hydrochloric acid. It forms bubbles of carbon dioxide gas.

Lodestone, a form of the mineral MAGNETITE, is naturally MAGNETIC.

Special PropertiesIceland spar, a form of the mineral CALCITE, produces DOUBLE REFRACTION.

PITCHBLENDE is an example of a mineral that is RADIOACTIVE.

Uses of MineralsOre- a mineral that contains METALS AND NONMETALS THAT CAN BE MINED AND REMOVED IN USABLE AMOUNTS FOR A PROFIT.

Metals- elements that have shiny surfaces and are able to conduct HEAT and ELECTRICITY.

Uses of Minerals

1. Iron Hematite

2. Aluminum Bauxite

3. Copper Chalcopyrite

4. Lead Galena

5. Silver Argenite

6. Gold Gold

7. Mercury Cinnabar

Alloy- a mixture of two or more metals or a mixture of metals and nonmetals

1. Tin + copper = bronze2. Copper + zinc = brass3. Iron + chromium + limestone = steel4. Lead + tin = pewter

NonmetalsNonmetals- elements that have dull surfaces and are poor conductors of HEAT and ELECTRICITY.

a. Halite- table saltb. Gypsum-wallboardc. Sulfur-matchesd. Talc-powdere. Graphite- pencil “lead”f. Kaolinite-Bricks

g. Calcite-Cement

Gems and Precious StonesGems- minerals that have the following desirable qualities.

Hardness, color, luster, clarity, durability, rarity.

1. Precious stones- diamonds, rubies, sapphires, emeralds2. Semiprecious stones- amethyst, garnet, topaz3. Gems that are NOT minerals- pearls, amber

Rocks!

How are rocks related to minerals?

Why study rocks??

They can tell us about the history of the Earth-Plants and animal fossils to tell us past living conditions.

We can read these rocks to discover past climates.

Predict where to search for oil and gas resources.

Geology- the branch of science that studies rocks.Rocks are CLASSIFIED on the basis of their FORMATION/ORIGIN.

The three groups of rocks are:

1. SEDIMENTARY2. IGNEOUS3. METAMORPHIC

Rocks in relation to mineralsMany kinds of rocks are composed of MINERALS.

B. Some rocks are MONOMINERALIC - composed of ONLY ONE MINERAL.

C. Most rocks are POLYMINERALIC- composed of TWO OR MORE MINERALS.

Common rock-forming mineralsThere are almost 3000 types of minerals, but only 8 of these minerals make up 90% of the rocks of Earth’s crust.

1. Quartz 12%

2. Potassium Feldspar 12%

3. Plagioclase Feldspar 38%

4. Pyroxene 11%

5. Hornblende/Amphibole 5%

6. Biotite Mica 5%

7. Clays 4.6%

8. Olivine 3%

9. Other 8.4%

Sedimentary RocksRocks that usually form in layers from accumulation of sediments, organic matter, or chemical precipitates.

Sedimentary Rocks

Types of Sedimentary RocksClastic- form from rock particles/sediments that are pressed and cemented together.

Compaction- pressed by weight of overlying rocks

Cementation- glued by natural cement in water (Calcite)

ESRT-Page 7 Clastic Sedimentary Rocks

Rock Name Grain Size (cm) Comment Map Symbol

Conglomerate Boulders 25.6Cobbles 6.4Pebbles .2

Various size rockParticles and mudSilt and SandCemented together

Sandstone Sand .006 Fine to coarse grains cemented together

Siltstone Silt .0004 Very fine grained

Shale Clay Compact, may split easily

Chemical Sedimentary RocksChemical- form from dissolved minerals in water that settle-out/precipitate. Dissolved minerals left behind when water evaporates.

Chemical Sedimentary Rocks-Pg. 7 ESRT

Rock Name Composition Comment Map Symbol

Limestone

Rock Salt

Rock Gypsum

Dolostone

Bioclastic Sedimentary Rocks

3. Bioclastic- formed from the accumulation of plant/animal matter that undergoes a transformation into rock.

Rock Name Composition/Comment

Limestone Cemented shell fragments

Coal Carbon from plant remains

Formation of Coal-Bioclastic Sedimentary Rock

Formation of CoalPEAT- accumulated plant material

LIGNITE known as BROWN COAL

BITUMINOUS known as SOFT COAL

ANTHRACITE known as SOFT COAL

Important Characteristics of Sedimentary Rocks1. They are composed of rock fragments or organic particles. a. Some have a range of particle or sediment size.

CONGLOMERATE

B. others consist mainly of one size of sediments- due to sorting during deposition

SANDSTONE

Characteristics of Sedimentary rocks2. Some are organic-they form from plant and animal remains.

FOSSIL LIMESTONE

3. FORM IN LAYERS CALLED STRATA OR BEDS.

SHALE

Igneous Rocks FormationA. Forms from the cooling and solidification/ crystallization of molten lava

and magma.

1. When molten lava or magma COOLS and SOLIDIFIES, crystals of different minerals form the rock.

The rock contains a crystalline structure of ingrown crystals of different SIZES, SHAPES, and COMPOSITION.

Types of Igneous Rocks1. Extrusive/Volcanic: forms from the fast cooling of lava on or near

Earth’s surface. Fast cooling does NOT allow time for crystals to grow.

Rocks have small or no crystals and thus a smooth/fine texture.

Types of Igneous RocksIntrusive/Plutonic: forms from slow cooling of magma within the Earth. Slow cooling allows time for large crystals to grow.

Rocks have large crystals, thus a coarse/rough texture.

Label the top diagram on page 17 with the following

Lava

Magma

Extrusive

Intrusive

Extrusive (Volcanic) Intrusive (Plutonic)

Rate of Cooling Very Fast Fast Slow

Grain Size non-crystalline Less than 1mm 1mm or larger

Texture glassy fine coarse

Examples obsidian basalt/rhyolite granite

Igneous RocksRelationship between CRYSTAL SIZE and RATE OF COOLING.

a. As the rate of cooling increases, the crystal size decreases.

Metamorphic RocksForm from other pre-existing rock (sed, meta, ign) that have been changed.

Conditions that cause rocks to undergo metamorphism

1. Heat2. Pressure3. Chemical Activity

Metamorphic RocksUnder conditions of high temperature and high pressure, many metamorphic rocks form by the process of RECRYSTALLIZATION. This is the growth of new mineral crystals from the crystals of an IGNEOUS or METAMORPHIC rock. Recrystallization occurs without true melting.

Metamorphic RocksD. Changes in rock caused by metamorphism.

1. Increased density2. Chemical change/new minerals3. Banding4. Distorted Structure

Types of Metamorphism1. Foliated- has mineral crystals arranged in parallel layers of “bands.”

2. Unfoliated- does NOT have mineral crystals in bands. Does not break in layers/sheets.

Contact Metamorphism

What will limestone and shale “change” into??

Review of the Rock Cycle

What should I study??

Make sure you know how to read/interpret pages 1, 6, 7, and 16 in ESRT

Go over your note packets.

Go over your practice Regents review questions.

Look over your study guide and quizzes.