• This term is used in several different ways.
• Health and fitness – extol the benefits of it
together with vitamins.
• Mining Industry – for anything taken out
of the ground (such as coal, iron core or
sand and gravel).
• Geologist – any naturally occuring
inorganic solid that possesses an orderly
crystalline structure and a well defined
chemical composition.

• Naturally occurring – It means that a
mineral should be formed by natural
geologic processes.
– This is why synthetic diamonds and rubies,
as well as variety of other usefuk materials
produced by chemist are not considered
as minerals

• Solid – In order for something to be
considered as mineral, it should be
solid at temperatures normally
experienced at Earth’s surface.
– Thus, Ice (Frozen water) is considered as
mineral whereas liquid water is not.

• Orderly Crystalline Structure – Minerals
are crystalline substances which
means their atoms are arranged in an
orderly, repetitive manner.

• This orderly packing of atoms is
reflected in the regularly shaped
objects we call crystals.
• Some Naturally occurring solids, such
as volcanic glass (obsidian), lack a
repetitive atomic structure and are
referred to as amorphous (without
form) and are CONSIDERED AS
MINERALS.

• Well-defined Chemical Composition – Most
minerals are chemical compounds made up
of two/more elements. A few (such as Gold
and Silver) consist of only a single element.
• The common mineral quartz consist of 2
oxygen (O) atoms for every Silicon (Si) atoms,
giving it a chemical composition expressed by
the formula SiO2. Thus, no matter what the
environment is, whenever atoms of Oxygen
and Silicon joined together in the rato of 2 to
1, the product is always quartz.

• Generally Inorganic
Inorganic – Substances such as stone and
metal that do not come from living things.
• Minerals are generally inorganic. Inorganic
crystalline solids, as exemplified by ordinary
table salt (Halite) that are found naturally are
considered minerals.
• Organic Compounds on the other hand, are
generally not.
• Ex. Sugar – (Crystalline like salt) comes from
sugarcane or sugar beets and is common
example of such an organic compound.

• Minerals and other earth materials are
composed of chemical elements.
• Elements – Fundamental
component of matter that cannot be
broken into a simpler particles by
ordinary chemical processess. (Most
common minerals consist of a small
number – usually 2 to 5 of different
chemical elements).

• Oxygen
• Silicon
• Aluminum
• Iron
• Calcium
• Sodium
• Potassium
• Magnesium

• In nature, most chemical elements
have either a positive (+) or
negative (-) charge.
– ION- atom with either positive/negative
charge
– CATION – Positively charged atom
– ANION – Negatively charged atom

• Most minerals are made up of 2-5
essential elements. Ex. Formula of
quartz is SiO2. One atom of Silicon for
every 2 atoms of oxygen.

• The mineral has a crystalline structure,
and therefore every mineral is a
crystal.
– Crystal – any solid element/compound
whose atoms are arranged in a regular,
periodically repeated manner

Ex. Mineral halite (common table salt)

• NaCl
– One sodium for every one chlorine
(You can see here
that the sodium &
chlorine ions
alternate in orderly
rows & columns
intersecting at right
angles. Figure 1.1 is
the crystalline
structure of halite).
Figure 1.1

• Crystalline Structure - orderly, repetitive
arrangement of atoms in a crystal.

As evaporation
continues, more
and more
sodium
& chlorine ions
would
precipitate onto
the faces of
the growing
crystal.

• Crystal Face – flat surface that
develops if a crystal grows freely in an
uncrowded environment. Under
perfect conditions, the crystal that
forms will be symmetrical.
– Symmetrical – has a corresponding similar
parts: in other words, one side is the same
as the other.

• This properties allow geologists to identify a
mineral in the field.
– Chemical composition
– Crystal structure
• But if you pick a crystal of a mineral( for
example, halite), you cannot see the atoms.
You should measure its chemical composition
and crystal structure by laboratory
procedures, but such analyses are expensive
& time consuming.
• Geologists commonly use properties to
identify minerals.

• Crystal Habit – characteristic shape of
an individual crystal & the manner in
w/c aggregates of crystals grow.
Geologists can
identify that this
mineral is a
prismatic quartz
because of its
elongated
shape.

• Cleavage – tendency of some
minerals to break along that surface,
which are planes of weak bonds in the
crystal. When a mineral has excellent
cleavage, sheet after sheet can be
peeled from the crystal, like peeling
layers from an onion.

• Fracture – a manner n which minerals
break other than along planes of
cleavage.
The type of
fracture shown
in this picture is
concoid.

• Hardness – resistance of a mineral to
scratching & is one of the most
commonly used properties for
identifying a mineral.

• Mohs Hardness Scale – after Friedrich
Mohs, he developed this scale in the
early 19th century.

This scale
was used to
measure the
hardness of
a mineral
more
accurately.

Mineral Hardness scale 1-10:
• Toronto Girls Can Flirt And Only Quit To Chase Dwarves .
• Terrible Giants Can Find Alligators Or Quaint Trolls Conveniently
Digestible
• Tall Girls Can Flirt And Other Queer Things Can Do!
• The Girls Can Flirt And Other Queer Things Castrate Donkeys!

• Color – most obvious property of a
mineral is often used in identification.
But color can be unreliable because
small amount of chemical impurities
can dramatically alter color.

• Streak – refers to the color of the fine
powder of a mineral. It is observed by
rubbing the mineral across a piece of
unglazed porcelain known as the
“streak plate”.

• Streak • Streak Plate

• Luster – manner in which a mineral
reflects light. A mineral with a metallic
look irrespective of color has a metallic
luster. As a result, it looks like gold & is
commonly called “fool’s gold”.

Pyrite
Mineral

•Metallic - Minerals with a metallic
luster are opaque and reflective,
like metal. The metallic elements,
most sulfides, and
some oxides belong in this
category.
•Opaque-

• chalcopyrite500

• Pearly - Describes a luster similar to the
inside of a mollusk shell or shirt button.

• Earthy- This luster defines minerals with
poor reflective qualities, much like
unglazed porcelain. Most minerals with
a dull luster have a rough
or porous surface.
• Porous- Containing rounded, tiny holes
throughout. Porous minerals are
lightweight and easily dyed.

• Resinous - This is the luster of many yellow,
dark orange, or brown minerals with
moderately high refractive indices -
honey like, but not necessarily the same
color.
• Refractive indices- The amount
of refraction that takes place in a
particular substance, which is a direct
connection to the speed of light in that
substance.

• Reaction to acid
• Magnetism
• Radioactivity

• Fluorescence - FluorescenceProperty
exhibited in certain minerals in which
they display a glowing effect when
having ample illumination
with ultraviolet light.

• Phosphorescence- Phosphorescence
• The ability of some fluorescent minerals
to keep on glowing for several
seconds after the fluorescent lamp has
been removed.
• these properties can be characteristics
of specific minerals

• Geologists classify according to their
chemical elements.
• Silicates, together w/ oxygen make up
about 42% of earth’s crust. They are
abundant for 2 reasons. First, silicon &
oxygen are the two most plentiful
elements in the crust. Secondly, silicon
& oxygen combine readily.

• Carbonate minerals are much less
common than silicates n earth’s crust,
but they are important rock-forming
minerals because they form
sedimentary rocks that cover large
regions of every continent. The shells &
other hard parts of the most marine
organisms such as clams, oysters &
corals are made of carbonate
materials.

• Commercially Important Minerals are
minerals from which metals / other
elements can be profitably recovered.
• Industrial minerals - rocks/ minerals that
have economic value exclusive of
metal ones, fuels & gems.

• Gem – mineral that is priced primarily
for its rarity and beauty although some
gems such as diamonds are also used
industrially.
• Precious Gems- Any of several gems,
including the diamond, emerald, ruby,
and sapphire, that have high
economic value because of their rarity
or appearance.