Minerals and Rocks

How are minerals related to rocks?

• All rocks are made of minerals.

• Those rocks made of one mineral are called monominerallic rock. Mono means one!

• Those made of 2 or more minerals are polyminerallic rocks. Poly means more than one!

What are Minerals?

•They are: “Naturally occurring, inorganic, solid, with a definite chemical composition, and a definite crystal structure.”

How do minerals get their chemical and physical properties?

• Properties result from the specific internal arrangement of atoms within the mineral itself

For example, how hard a mineral is, what crystal shape the mineral has etc. are all caused by the arrangement of it’s atoms/molecules.

Silicon-Oxygen Tetrahedron

• The most common arrangement is the silicon-oxygen tetrahedron of the silicate minerals which are in great concentration in the crust

Looks Like:

Note the pyramidal shape!

Examples:• Feldspars: most abundant minerals• Quartz: second most abundant

Carbonate Minerals• Have CO3 (carbonate group) as their

constituent units

• Calcite: CaCO3

Silicates

• Quartz: Chemical Formula: SiO2

Oxides

• Hematite: Chemical Formula: Fe2O3

Physical Properties of Minerals; used for

identification• Mineral ID is accomplished through the

use of a combination of tests:– Color– Luster– Streak– Hardness– Cleavage and Fracture– Density and Specific Gravity– Special Properties (if they exist)

Color• Most often used, but least reliable!

• Many different minerals can have the same color

Olivine Green Quartz

Luster• The way a mineral reflects light

• Nonmetallic Luster:

• Metallic Luster:

Streak• Color of a mineral when powdered

• Done by scraping a mineral across an unglazed porcelain tile

Hematite has a reddish brown streak

Hardness• The resistance of a mineral to being

scratched• Compared to the 10 minerals of Moh’s

Hardness Scale; Talc (1) to Diamond (10)

Cleavage and Fracture

• Cleavage: when a mineral splits along flat planes

• Fracture: when a mineral breaks irregularly

Muscovite: perfect cleavage

Density and Specific Gravity

• Density of a mineral is a very specific characteristic

• Specific Gravity: the ratio of the weight of a substance to the weight of an equal volume of water at 4ºC

• Both properties are distinctive of particular minerals

Special Properties

• Some minerals possess properties that are all their own:

• Magnetite: Has enough iron in it to be attracted to magnets.

• Iceland Spar Calcite: double refraction• Calcite: fizzes in the presence of HCl• Etc. Ex. Iceland Spar:

Special Properties Continued

• Pitchblende: Radioactivity: gives off invisible radiation

• Fluorite: Fluorescence: some minerals glow in ultraviolet light

Using Common Properties of Minerals Homework

•Complete the packet using the chart on the last page of your reference table.

•Do your best!!!!

Classifying Minerals Lab

• You will be identifying 8 unknown mineral samples on the basis of their physical and chemical properties

• Work carefully.

• Make sure to always wear your safety glasses.

Introduction to Rocks

• Rocks: solid substances which are made of 1 or more minerals

Igneous Rocks• Form from hot liquid rock.Two types:1)Intrusive Igneous Rocks: form

from hot liquid magma inside the earth. Cools SLOW!!! (underground)

BIG Crystals!

Igneous rocks continued:

• 2) Extrusive Igneous Rocks: Cool QUICKLY on the Earth’s surface from lava.

• Have small crystals or none at all!

• Lava is the same as magma. It’s name tells you it’s location.

Igneous Rocks: Composition

• Classified by composition and texture

• Composition:– Felsic (high aluminum content)– Lower density; lighter color

– Mafic (high iron & magnesium)– Higher density; darker color

Igneous Rocks: Texture• Texture: gives clues about the

environment the rock formed in• SLOWER COOLING produces: Coarse Grained Texture:

– Large crystals (1-10mm) means slow cooling deep underground

• FAST COOLING produces: A) Fine Grained Texture:

– Small crystals (<1.0 mm) means fast cooling on the surface

B Glassy Texture:– NO CRYSTALS-nearly instantaneous

cooling

Igneous Rock Key Words• Molten: means liquid• Solidification: means freezing• Crystallization: means freezing• Vesicular: means has gas pockets

(bubbles)• “IT IS AN IGNEOUS ROCK BECAUSE IT

HAS INTERGROWN CRYSTALS!!”

Igneous Rock Classification Chart

Igneous Rock Chart Practice• Page 6 ref. tables

• 1. If an igneous rock has a lot of gas pockets, will it be called vesicular or non-vesicular?

• 2. What is the name of the igneous rock that has a low density, has a coarse texture and is intrusive?

• 3. Along the line that separates granite and diorite,,,,what is the percentage of plagioclase feldspar? (Measure and line up from zero.)

• 4. Name a mafic rock that is fine grained and vesicular.

• 5. A coarse grained rock is made up of 60% plagioclase feldspar, 18% biotite, and 22% amphibole. Name the rock……

Igneous Rock Exercise Homework

• Answer the questions using page 6 of your reference tables.

Sedimentary Rocks• 2 Main Groups:

1) Inorganic Land Derived Sedimentary Rocks

Rocks formed from sediments that are compacted and cemented

2) Chemically and/or Organically Formed Sedimentary Rocks

Inorganic Land Derived Sed. Rocks

• Generally result from river, lake, or deep ocean deposits

• Classification is based on SIZE of the sediment particles

• Process of Formation:– Sediment is deposited– Sediment is compacted-pressed down– Sediment is cemented- “glued together”

Ex. Sandstone, conglomerate, siltstone, shale

Chemically and/or Organically derived Sed.

Rocks• Chemical formation:

– Evaporation of solutions– Precipitation of particles from

solution• Ex: rock salt, rock gypsum,

dolostone, chemical limestone

• Organically formed:– Animals (shells): limestone– Plants : coal

Sedimentary Basin Diagram

Sedimentary Rock Classification Chart

Sedimentary Rock Key Words

• Lithification: changing sediments to rock• Compaction: pressing sediments• Precipitation: crystallize out of solution• Stratification: layering• Fossils: only found in sed. rocks• Cementation: “gluing” sediments together• Clastic: pieces of other rocks

“It is a sedimentary rock because it has sediments cemented together!!”

Sedimentary Rock Exercise Homework

• Answer each of the questions using page 7 of your reference tables

Metamorphic Rocks

• Metamorphic means “changed”• These rocks were once sedimentary,

igneous or even metamorphic!• “Heated and squeezed” WITHOUT re-

melting.• Commonly found along crustal plate

boundaries where pressures are great.

Contact Metamorphism• A process where an igneous intrusion (a

channel of hot magma moving up through the crust) comes into contact with neighboring rocks

• This causes the parent rock (rock around it) to metamorphose

Metamorphic Rock ID Chart

Metamorphic key words

• Foliated: Minerals have rearranged in to layers. Called banding when they can be easily seen. Ex. Gneiss

• Non-foliated: Minerals may have grown but are not rearranged.

• Distorted Structure: Fossils in once sedimentary rocks are stretched and out of shape due to extreme heat or once parallel layers are now wavy gravy!

Metamorphic Rocks Exercise Homework

• Answer each of the questions using page 7 of your reference tables.

Rock Cycle• The continuous, dynamic set of processes by

which rocks are changed into other types of rocks.

p. 6 Ref Tables:

“Rock ID Laboratory”

• Move around the room and ID each of the numbered samples.

• You can start anywhere, but you must attempt to ID each of the samples.

Climate, Rock, and Mineral Test

• Prepare for the “rockiest” test you have ever taken!!!

• Study, Study, Study…………………..