Geol: 2081: Mineralogy
(c) copyright B. Dutrow 2006

"Minerals are the basic stuff of the Earth, and their study will always remain at the core of the Earth Sciences."
- Frank Hawthorne, 1993

Minerals: We walk on them, we wear them, we wash our clothes with them, we may even brush our teeth with them. They bring electricity into our lives and provide the building materials for our homes and schools. Without minerals, we would not have an Earth!

Banded Iron Formation - Australia

Goals of the course
To understand what these materials are, that are an integral portion of our life:
As citizen's of the Earth, and as students of geology.

To provide a solid foundation in conceptual aspects of mineralogy:
What minerals are, how they form, how they are analyzed and  described, how they behave as a function of P-T-X, how they are classified, identified, and utilized.
To understand their utility in the study of our Earth:
Because these materials are the products of complex Earth and Planetary processses that occur over a wide range of temperatures and pressures, minerals can tell us  conditions of formation and subsequent evolution of the continents and ocean basins.

Pallasite meteorite,  photo courtsey of the Smithsonian Institution
To provide linkages to other areas of geology:
petrology, geochemistry, geophysics, structural geology, meteoritics, environmental geology, geomicrobiology, economic geology

Hawthorne, 1993

Recent and fossilized pinecones
To connect with  other fields of study:
inorganic chemistry, material science, gemology, soil science, biology, nanoscience, art, archeology

Uxelite, a mineral that behaves as a fiber optic
To understand their central role in our standard of living,
Have fun learning how the Earth works!

We will apply principles learned from each portion of the course as we proceed......

Lecture material concentrates on concepts and principles 

Lab exercises put these  principles to use where we descibe and identify hand specimens

Mineralogy  & MINERALS

 Mineralogy, or Mineral Science, is the study of minerals.

This encompasses:

- crystallography (where we'll start)

    - how chemical elements make minerals

- crystal chemistry
   - relates chemical composition, internal structure, and

- physical properties

- identification

- classification

- geologic occurrence
   - how and where they form

Staurolite, Russia

         *  We are all familiar with minerals
We are all familiar with Minerals

diamond in matrix

White, Black, Green, Pink
Household items
Mud after a rainstorm

Minerals are the building blocks of the EARTH!


Naturally occurring
formed by natural processes
synthetic = lab made
excludes liquids and gases
highly ordered atomic arrangement, an internal structural framework of atoms (ions) arranged in a regular, repeating, geometric pattern (periodic)

solids that lack an ordered atomic arrangement are amorphous
definite chemical composition
definite but not fixed, within limits (or range) of compositions and can be expressed as a chemical formula: e.g. FeS
formed by inorganic processes, usually
it is increasingly recognized that minerals may be produced organically e.g. magnetite in bird brains, aragonite in shells = biomineralization

plagioclase feldspar, labradorite, Madagascar

There are ~ 4200  known mineral species.

  • About 100 are common (we will learn these)
  • a few dozen are considered abundant.
This is minor compared to the biological world; there are more than 10,000 species of inchworms alone!


mineral-like but lack all the qualifications (opals)

Naming of minerals
after properties, place, people
Minerals   Not minerals
quartz - SiO2   opal
ice   CO2
snow   granite
biotite   volcanic glass
diamond   oil
serpentine   amber


Rock   Not a rock
quartzite   quartz
granite   sand, soil


Began with mineral's Uses
Minerals and rock were selected and used for certain  purposes                long before humans even devised a written language.

The prehistory of humanity is dated by the materials with which our predecessors made their tools.

One of our first scientific acts was to distinguish between different rocks and minerals and use them as tools according to their properties.
"Stone  and the Stone Age"

Our early ancestors were vegetarians, when their  ancestors became omnivorous,  the use of tools was essential.

Realized suitibility of certain materials,
 e.g. obsidian and flint became widely used.

  Fire was started by striking pyrite with flint.
  Naturally-occurring poisons such as arsenic were known and used.

Toward the end of the Neolithic, ca. 40 different rocks and minerals were in use.
"Metals and the Bronze Age"

Naturally occurring native metals were greatly sought after by Stone age humanity for their curiosity and ornamental value rather than for tool making.

Discovered that heating metals greatly promotes the ease with which they can be worked and extracted.
e.g. the origin of the discovery of bronze; early bronze was a mixture of Cu and As.

Metals have been used for at least 4000 yrs;  prehistoric man was also known  to mine and smelt metallic minerals  to produce Au, Ag, Fe, Cu, Pb and bronze.
e.g. Hg was in  use in Egypt as early as the 15th-16th C BC and
  the old Testament  of the Bible refers to the use of Au, Ag, Cu, Sn, Pb and Fe.
"Iron Age"

About 1400 B.C.

Fe is hard, durable and abundant

Throughout the Stone, Bronze and Iron ages, humanity also began to use an increasing number of minerals unrelated to the manufacture of tools.
Fascination with ART seems an intrinsic property of the human psyche.
Cave art is our earliest record.

Colored pigments became common; red and black pigments (hematite and  pyrolusite, Mn oxides) were used for cave painting for over 5000 yrs.

Other minerals (jade,  amethyst, garnet) were used for ornamentation or the diverse hard  minerals and rocks
 used for tools and weapons (jade, flint,  obsidian).



    * Indian, 1100 B.C.

    * First written work on minerals is by Greek philosopher Theophrastus
        (372-287 B.C.) and Pliny 300 yrs later.

    * Emergence of mineralogy as a science is credited to German physican
        Georgius Agricola with the publication De Re Metallica in 1556.

    * 1669 Steno and his law.
            Interfacial angles of quartz xls are constant, no
            matter what the size and shape of the crystal is.
            This discovery lead to the science of crystallography.
            He was beatified in 1988 by the pope

    * followed by the physics of minerals

        -early 19th century, rapid advances with the
                development of instruments which could measure
                precisely angles between xl faces.

    *  the chemistry on minerals.

         - 1854 Dana introduced the chemical classification  used today.
            e.g. bk. After J.D. Dana...

    * 20th century,
        - 1914 Braggs solved the first crystal structure.

    * Now rapid advances in instrumentation and techniques for measuring and imaging
exact positions of atoms in a crystal.
Linus Pauling, the Nature of the Chemical Bond


1.  CRYSTALLINE - characteristic of a mineral; long range 3D internal structural order

2.  CRYSTAL - when external form is bounded by geometric forms

        - external form is function of growth environment and may not reflect internal order.

        We use term in broader sense to indicate ordered 3D structure.
Staurolite, Urals, Russia

3. Crystal GROWTH

        - grow from nucleus by accretion from soln, melt or vapor

        - grow from outside cf. plants

        -  amount of space available for growth determines shape

4. MORPHOLOGY - external form of mineral

    (a) euhedral = well formed faces
 Pyrite, Spain

    (b) subhedral = partial xl faces

    (c) anhedral = no xl faces

    (d) microcrystalline = xls observable with microscope
 Tiger's Eye, Australia (SiO2 replaced Amphibole)

    (e )cryptocrystalline = xl resolved with x-rays

    (f) amorphous = no long range order
Opal, Australia

5. CRYSTALLOGRAPHY - study of crystalline materials (Steno),
        crystal symmetry, orientation of atoms in xl.

    (a) direct imaging of internal arrangement e.g. TEM

    (b) relationship between xl faces - symmetry

Two methods to describe positions of atoms in xline matter:

    (a)Translational - spatial relationships

    (b)Rotational - relationships between faces

B. dutrow