Atoms, Elements, and Minerals

Atoms are composed of protons (+), neutrons, and electrons (-). A given element always has the same
number of protons. An atom in which the positive and negative electric charges do not balance is an
ion.

Ions or atoms bond together in very orderly, three-dimensional structures that are crystalline.

A crystalline substance is considered a mineral (in geologic terms) if it is naturally occurring
and inorganic and has a definite chemical composition.

The three most abundant elements in the earth's crust are oxygen, silicon, and aluminum. Most
minerals are silicates, with the silicon-oxygen tetrahedron as the basic building block.

Feldspars are the most common minerals in the earth's crust. The next most abundant minerals are
quartz, the pyroxenes, the amphiboles, and the micas. All are silicates.

Minerals are usually identified by their physical properties. Cleavage is perhaps the most useful
physical property for identification purposes. Other important physical properties are external
crystal form, fracture, hardness, luster, color, streak, and specific gravity / heft.

The interaction between the internal and external forces of the earth is illustrated by the rock
cycle, a conceptual device relating igneous, sedimentary, and metamorphic rocks to each other, to
surficial processes such as weathering and erosion, and to internal processes such as tectonic
forces. Changes take place when one or more processes force earth's material out of equilibrium.

Plummer’s summaries are available on-line – see the link in my sources for more materials including
interactive quizzes and a glossary. (VH)

cleavage- The ability of a mineral to break along preferred planes.


crystal form- Arrangement of various faces on a crystal in a definite geometric relationship to one
another.


fracture- The way a substance breaks where not controlled by cleavage.


hardness- The relative ease or difficulty with which a smooth surface of a mineral can be
scratched; commonly measured by Mohs' scale.


luster- The quality and intensity of light reflected from the surface of a mineral.


streak- Color of a pulverized substance; a useful property for mineral identification.


specific gravity- The ratio of the mass of a substance to the mass of an equal volume of water,
determined at a specified temperature.


Color is likely to be the first physical property you notice about a mineral sample, but it may not
help that much to identify a mineral. Many minerals can be the same color, but because of trace
elements, different samples of the same mineral often have different colors.



Write the definitions of these terms:

Matter –

Atom –

Element –

Compound -

Crystal –


Crystaline solid –



Can you pronounce the most abundant elements in the Earth’s crust correctly?


Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium.


Pronounce some other elements:





Which elements have the stress (přízvuk) on the second syllable?





Fill in the gaps with a suitable expression:

Although    account     designated     despite     key    resembles    unlike   whereas


Each element is ________________  by its atomic number.

Oxygen and silicon _______________ for almost seventy-five percent of elements in the earth’s
crust.

Magnesium ________________ aluminum in many ways.

Iron is _______________ aluminum.  Iron is heavy, ______________ aluminum is light.

_______________ copper and aluminum are both good conductors, aluminum is used in aviation because
it is far lighter.


_________________   the great number of minerals and many differences among minerals, all minerals
have four things in common. Each mineral is a mixture or a combination of certain __________
elements.


Explain the words in bold type:

Conductors =                            , in common =

Make these negative:


____organic,  color___ ,   ____regular,


Compare:

Heavy -____________________, dense - ______________, abundant - ___________________

Light - ____________________, dark - _______________,