GeoLOGY 101 Lab Lecture Outline

chemistry and Minerals (Lab 3)

 

I. Lecture Content - Topics

Matter and Its Physical States

Elements, Atoms, and Isotopes

Chemical Bonding and Compounds

Crystals and Minerals

Defining a Mineral

Classification of Minerals

The Silicate Mineral Group

The Carbonate Mineral Group

Other Mineral Groups

Mineral Identification

Focus on The Major Rock-Forming Minerals

Mineral Resources and Reserves

 

II.  Physical States of Matter

      A.  Definition of Matter

              1. Anything that has mass and occupies space

·       Atoms and molecules

·       All Earth materials

 

                2. The intimate relationship between matter and energy

·       Einstein's famous equation - E = mc2

 

       B. The Four Different States of Matter

                1. Solid

                2. Liquid

                3. Gas

                4. Plasma

 

       C. Transformation of Matter from One State to Another

                1. Also called a "phase change"

 

2. Always involves a condition change in the system

 

                3. Change in physical state always involves a process

 

4. Many major Earth processes involves a phase change

 

III. Elements, Atoms and Isotopes

       A. Elements: Basic Building Blocks of Earth Materials

                1. There are 92 naturally occurring elements on Earth

·        Most created in (an) ancient star(s)

·        Each element has a name and a symbol

·        Organized in the Periodic Table of Elements

·        Range in mass from Hydrogen to Uranium

 

2. Most Common Elements in Earth's Crust

ü    Oxygen (63%)

ü    Silicon (28%)

ü    Aluminum (8%)

ü    Iron (5%)

ü    Calcium (4%)

ü    Sodium (3%)

ü    Potassium (3%)

ü    Magnesium (2%)

 

2. Elements are composed of tiny particles called atoms

·        Smallest units of matter that characterize elements

·        Atoms are composed of even smaller particles

 

3.  Atoms have an organized internal structure

·        Center of atom consists of nucleus (positively-charges protons and neutral neutrons)

 

·        Outer part of atoms consists of a "cloud" of negatively-charged electrons

 

4. Number of protons in an atom = the type of element

·       Called the atomic number

5. The sum of protons and neutrons in an atom determines

 the element's atomic mass

 

·       Called the atomic mass number

 

6.  Atoms of a single element can vary in atomic mass

·       Proton # same; Variation in neutron #

·       Called "isotopes"

·       Most isotopes are stable; some are unstable

 

IV. Chemical Bonding, Molecules & Compounds

       A. Bonding of Atoms into Molecules & Compounds

1. Molecule defined: A substance made up of two or more

        atoms that are bonded together

 

2. Compound defined: A substance made up of atoms from

       two or more elements that are bonded together

 

3. Ions defined: are atoms, molecules, or compounds that

        have either, more, or less electrons (-) than the

number of protons (+)

 

·       Ions possess an electrical charge (+ or -)

·       Compounds that are ions are called radicals

 

4. Bonding defined: The process of joining together two

      or more atoms into molecules or compounds

 

5.  Bonding is caused by the interaction of the electron

       clouds between closely adjoining atoms and/or

       molecules

 

                5. Two major types of chemical bonding

·       Ionic

·       Covalent

 

6.  Two other types of chemical bonding

·       Metallic

·       Van der Waal

 

       B. Ionic Bonding

1. The formation of a compound by the electromagnetic

        attraction of oppositely-charged ionic substances

·       Involves the transfer of electron(s)

·       Example: Halite (sodium chloride)

 

                2. Neutral ionic compounds are called salts and consist of

                        a pair of ions

·       Cation (positively-charged ion)

·       Anion (negatively-charged ion)

 

3.  Ionic bonds are relatively weak (easily broken)

 

      C. Covalent Bonding

              1. The formation of a molecule or compound by the sharing

                        of the outermost electrons between atoms

 

·       Examples:

ü    Diamond (C-pure carbon)

ü    Silica radical (SiO4)-4

ü    Carbonate radical (CaCO3)-2

 

2. Covalent bonds are relatively strong compared to ionic

 

3. Minerals consist of compounds that typically have both

        ionic and covalent bonds

 

V. Crystals and Minerals

      A. Crystalline Substances

                1. Crystals are highly-ordered, solid substances having a

                        regular, three-dimensional framework

 

·       Ordered internal atomic arrangement

·       Unit structures are of atomic scale

 

2. When completely unimpeded, crystals will grow with into

      perfect geometric forms, that reflect their unit structure

 

3. Not all solid, rigid substances are crystalline

 

·       Called amorphous - lack crystal structure

·       Examples are glass, obsidian & opal

               

B. Mineral - Defined

                1. Naturally occurring

                2. Inorganic

                3. Crystalline solid

                4. Narrowly defined chemical composition

                5. Characteristic physical properties

      C. Over 3,500 Different Minerals Have Been Recognized

Ø    See Mineral Glossary on Teacher's Web Page

 

VI. Classification of Minerals into Groups

A. The Silicate Group

        1. Characteristics of the Silicate Group

·       Base compound is the silica radical (SiO4)-4

·       Basic structure is the silica tetrahedron

·       Vast majority of rock-forming minerals found in the crust and mantle belong to the silicate group

 

2. The Silicate Group has several subgroups that are based

        on their arrangement of silica tetrahedral:

 

·       Olivine Group

·       Pyroxene Group

·       Amphibole Group

·       Mica Group

·       Clay Mineral Group

·       Quartz Group

 

3.  The Silicate Group can also be divided into two groups

        based on chemical composition

 

·       The Ferromagnesian Silicates

ü    Olivine

ü    Pyroxenes

ü    Amphiboles

ü    Dark-colored Micas

 

·       The Nonferromagnesian Silicates

ü    Quartz

ü    Plagioclase feldspar

ü    Potassium feldspar

ü    "White" micas

 

4. Silicate group minerals form primarily in igneous and

        metamorphic rocks, but are also present as detritus

        in sedimentary rock and sediments.

 

5. Hand samples of the different silicate subgroups:

 

B. The Carbonate Group

       1. Characteristics of the Carbonate Group

·       Base compound is carbonate radical (CaCO3)-2

·       Carbonate minerals are restricted to the crust

 

2.  Carbonate minerals form mainly form in sedimentary

       and metamorphic rocks

 

                3. Most typical carbonate minerals are calcite, aragonite,

                        and dolomite.

 

                4. Hand samples of carbonate minerals

                                               

D. Other Mineral Groups

       1. The Oxide Group

        2. The Sulphide Group

        3. The Halide Group

        4. The Sulphate Group

 

VII. Mineralization Processes

A. Minerals Can Grow in Various Environments

                   1. Crystallization from magma and lavas

·       Igneous mineralization

 

                   2. Crystallization from an aqueous solution

·       Hydrothermal mineralization

 

·       Sedimentary mineralization

 

                   3. Neo-crystallization and re-crystallization in the solid stat

·       Metamorphic mineralization

 

VIII. Identification of Minerals

       A. Physical and Chemical Properties of Minerals

 

                1. Luster & Color

                2. Cleavage & Fracture

                3. Hardness

4. Crystal Class

5. Mineral Habit

6. Density (specific gravity)

7. Reaction to acid

8. Magnetic susceptibility

9. Reaction to ultraviolet light

      10. Radioactivity

              11. Taste

B. Optical Properties of Minerals

                1. Refraction of polarized light through minerals

·        Each mineral has a unique light refraction value

·        Based on both crystal structure & composition

 

       C. Atomic Properties of Minerals

                1. Interaction of X-rays and mineral crystals

·        Each mineral has a unique X-ray pattern

·        Based on both crystal structure & composition

 

D. Techniques Used for Identifying Minerals

        1. Hand sample (bare eye) identification

        2. "Blowpipe" flame-jet technique

        3. Polarizing microscope

        4. Atomic absorption

        5. Electron-beam microprobe

        6. X-ray diffraction or fluorescence

        7. Nuclear (neutron activation)

 

IX. The Major Rock-Forming Minerals

      A. Rock defined:

1. An aggregate of crystals consisting of one or more

mineral species

 

                2. Two exceptions are obsidian (natural glass) and coal

 

      B. Only About a Dozen Major Rock-Forming Minerals

Form the Bulk of Earth's Lithosphere

 

Ferromagnesian Silicates (mainly igneous & metamorphic)

 

                     1. Olivine - (Mg, Fe)2SiO4

 

                        2. Pyroxene group - Ca, Mg, Fe, Al-silicate

·        Augite species most common

 

                        3. Amphibole group - H2O, Na, Ca, Mg, Fe, Al-silicate

·        Hornblende species most common

 

4. Biotite - hydrous K, Mg, Fe, Al-silicate

 

Nonferromagnesian Silicates (all three rock types)

 

5. Quartz - SiO2

 

6. Potassium feldspar - KalSi3O8

·        Orthoclase & Microcline most common

 

7. Plagioclase feldspar group -

·        Varies from CaAl2Si2O8 to NaAlSi3O8

 

8. Muscovite - hydrous K, Al silicate

 

9. Clay group - variable hydrous Al silicate

 

Carbonates (sedimentary & metamorphic rocks)

 

10. Calcite - CaCO3

 

11. Dolomite - CaMg(CO3) 2

 

Sulphates (exclusively sedimentary rocks)

 

12. Anhydrate - CaSO4

 

13. Gypsum - CaSO4 . 2H2O

 

Halides (exclusively sedimentary rocks)

 

14. Halite - NaCl

 

                Oxides  (all rock types)

                        15. Magnetite - Fe3O4

                        16. Hematite - Fe2O3

                        17. Limonite - hydrated iron oxide

                Sulfides (all rock types)

                        18. Pyrite - FeS2

                        19. Galena - PbS

                        20. Chalcopyrite - CuFeS2

                        21. Sphalerite - (Zn, Fe)S

 

X. Mineral Resources and Reserves

       A. Resource & Reserve defined by the U.S.G.S

              1. Resource:

A concentration of naturally occurring solid, liquid,

                 or gaseous material in or on the Earth's crust in such

                 a form and amount that economic extraction of a

                 commodity from the concentration is currently or

                 potentially feasible.

 

                2. Reserve:

That part of a resource base that can be currently economically extracted (given today's market price)

 

B. Factors That Define a Resource From a Reserve

        1. Total abundance of mineral

        2. Degree of concentration of a mineral

        3. Geographic location

        4. Political location

        5. Market commodity price

        6. Technological expertise

        7. New markets and uses

C. Nonfuel Mineral Production in the United States

        1. Compare Figures in Table 2.8

 

        2. About $40 billion a year in mineral commodities extracted

                from U.S. mines

 

        3. The major mineral commodities extracted in the U.S

·       Sand and gravel

·       Cement

·       Crushed stone

·       Gold

·       Copper

·       Silver

·       Iron ore

·       Lead

·       Magnesium metal

·       Boron

·       Phosphate rock

·       Clays

 

D. Interesting Fact about Metal Resources

·       About 75% of all metals mined in the world come

                from about only 150 locations

 

E. Virtually All Mineral Resources are Nonrenewable

·       World's richest deposits have already been mined

 

XI. Vocabulary Terms


Amphibole

Atom

Atomic mass number

Atomic number

Biotite

Bonding

Calcite

Carbonate mineral

Cleavage

Compound

Covalent bond

Crystalline solid

Dolomite

Electron

Electron cloud

Element

Ferromagnesian silicate

Gypsum

Halide

Hardness

Ion

Ionic bond

Luster

Mineral

Muscovite

Native element

Neutron

Nonferromagnesian silicate

Nucleus

Olivine

Potassium feldspar

Plagioclase feldspar

Proton

Pyroxene

Quartz

Reserve

Resource

Rock

Rock-forming mineral

Silica

Silica tetrahedron

Silicate