Geology
Chapter 3
1.
Minerals—The Building Blocks of Rocks
Define a mineral.

A mineral is a naturally occurring, inorganic crystalline solid that has a
narrowly defined chemical composition and characteristic physical
properties.
2.
In which three ways do minerals differ?

Minerals differ by chemical composition, crystalline structure and
physical properties.
3.
What do the protons, neutrons and electrons indicate about an element?

Electrons determine how the atom interacts with other atoms.

Protons determine the atomic number and the number of electrons
present when neutrally charged.

Neutrons can vary in number, which determine which isotope of the
element is present.
4.
What is the difference between an isotope and an ion?
a. An ion is an electrically-charged atom produced by adding (anion) or
reducing (cation) the number of electrons present.
b. An isotope is an element that differs by the number of neutrons
present in the nucleus.
5. Identify the four types of bonds that can exist between atoms and state the
significance of each.
a. Ionic: transfer of electrons creating an electrostatic attraction
b. Covalent: sharing of electrons between atoms
c. Metallic: metal to metal bonds
d. Van der Waals: weak residual bond between more strongly-bonded
layers
6. Identify the bonding for the following minerals: diamond, halite (rock salt),
graphite, copper.

Diamond: covalent bonding in 3-D

Graphite: covalent bonding in one direction, van der Waals bonding
between covalent bonded sheets

Halite: ionic bonding

Copper: metallic bonding
7. Explain the significance of this statement to minerals: Ordered internal
atomic arrangement is externally manifested.

The external form of a particular mineral is controlled by the internal
arrangement of the atoms or its internal structure.
8. Why are most metals good thermal and electrical conductors?

Metals possess electrons that are very mobile. Electrons in metals
tend to be easier to remove from the outer shell.
9. What are the eight most common elements in the crust (from first to last)?

Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Potassium and
Magnesium.
10. What are the eight mineral groups? Which criteria are the mineral groups
based upon?

Silicates, Carbonates, Native Elements, Sulfides, Oxides, Sulfates,
Halides and Phosphates. These groups are classified by anionic
endings.
11. List the physical properties of minerals? Why must you rely upon more than
the color of the mineral to identify it?

Color, streak, luster, hardness, fracture, cleavage, specific gravity,
crystal form, and tenacity. Other minor properties include taste, feel,
magnetism, fluorescence and effervescence.

Ex. Hematite can be brown, red or silver metallic, yet it always
produces a red-brown streak.
12. How does cleavage relate to the internal structure of the mineral?

Breakage or splitting occurs along smooth plane or planes of weakness
determined by the strength of the bonds within individual mineral
crystals.
13. What causes variation within a specific mineral?

Some minerals have a specific chemical formula; others have a range of
compositions. Galena (PbS) vs. Plagioclase Feldspar, which ranges
from calcium-rich (CaAl2Si2O8) to sodium-rich varieties
(NaAl2Si2O8). The mineral is dependent upon the ratio of calcium
to sodium.

Also, some minerals have the same chemical composition but different
bonding or crystalline structures (diamond vs. graphite; gypsum vs.
selenite)
14. Which group of minerals is the most abundant?

The silicates
15. The ten minerals in Moh’s Hardness Scale.

talc, selenite (or gypsum), calcite, fluorite, apatite, orthoclase, quartz,
topaz, corundum and diamond
Mineral Groups-Chapter 3
Mineral Group
Anionic
Ending
Rock Association (s)
Mineral Example
Silicates
Hornblende (pyroxene)
(Ca,Na)2-3(Mg, Fe, Al)5Si6(Si, Al)2 O22(OH)2
Augite (amphibole)
Quartz
SiO
Plagioclase Feldspar
NaAlSi3O8
Potassium Feldspar
CaAl2Si2O8
Mica
(biotite)
(muscovite)
Olivene
Carbonates
Calcite
Dolomite
Sulfides
Pyrite
Galena
Chalcopyrite
Sulfates
Anhydrite
Gypsum
Selenite
Oxides
Magnetite
Hematite
K
Halides
Halite
Fluorite
Native elements
Copper
Gold
Silver
Graphite
Diamond