Download What is a Mineral?

What is a Mineral?
• It is a naturally occurring , inorganic solid, with
a specific chemical composition and a definite
crystalline structure
Pyromorphite
What do all minerals have in
common?
All:
1. Are formed by natural processes.
2. Are NOT alive and NEVER were alive
(INORGANIC)
3. Have a definite volume and shape (hard solid)
4. Are elements or compounds with a unique
chemical makeup
5. Are made up of particles that are arranged in
a pattern that is repeated over and over
(called a CRYSTAL)
How minerals form?
• They are four major processes by which
minerals form:
1. Crystallization of magma.
2. Precipitation
3. Changes in pressure and temperature.
4. Formation from Hydrothermal solutions.
Crystallization from Magma
• When the magma as liquid cools to a
solid state, then forms crystals.
• Size of crystals depends on
• 1) the rate at which the magma/lava
cools.
• 2) the amount of gas the magma/lava
contains,
• 3) the chemical composition of the
magma/lava
Precipitation
• The water in Earth’s lakes and rivers beneath
its surface contains many dissolved
substances. When the water evaporates ,
some of dissolved materials can react to form
minerals.
Pressure and Temperature
• An increase in pressure can cause a mineral to
recrystallize while still solid.
• Changes in temperature can cause certain
minerals to be unstable. Under these
conditions, new minerals can be formed.
Hydrothermal solutions
• It is a hot mixture of water and dissolved
substances. They have temperature about 100
-300 C.
Ex: Sulfur minerals , Bornite
Watch Classifying Minerals Clip
Mineral Groups in the Earth’s Crust
Minerals that form the rocks within Earth’s crust belong to Seven
(7) main mineral groups:
( we will focus on the first three)
1) Silicates
2) Carbonates
3) Oxides
4) Sulfaes
5) Halides
6) Sulfides
7) Native
Hints to Classify Mineral Groups
A
Mineral groups that end with
“ate” and have an oxygen
group in its chemical formula
are one of the following;
Silicates = Si + Ox
Olivine
(Mg,Fe)2SiO4
Barite BaSO4
Sulfates = S + Ox
Carbonates = C + Ox
Calcite CaCO3
Mineral Groups
1 Silicates
)
Silicon and oxygen are the most common elements in
earth’s crust.
 A mineral group that has silicon and oxygen as part of their
atomic
structure.
 The most dominant mineral class is the silicates.
 Comprise more than 96% of the crust.
 All silicate minerals have the same building
block:
Silicon-Oxygen Tetrahedron
- consisting of four oxygen ions
(negative) surrounding one small
silicon ion (positive), forming a
tetrahedron, a pyramid shape with 4
identical faces.
Mineral Groups
1 Silicates
)
Mineral Groups
1 Silicates
)
Rock forming Silicates are
divided into two (2) groups:
Simatic Silicates (Ferromagnesium)

rich in silicon and magnesium (Iron).

main rock type found in the ocean floor and
comprise less than 15% of the crust.

mineral are dark in color.
Mineral Groups
4 Oxides
 compounds consisting of an atomic structure of oxygen
) combined with one or more metals.
 most common oxides are those of iron (Fe2O3) and aluminum
(Al2O3), referred to as Ore - Minerals.
5 Halides
)  compounds consisting of an atomic structure of chlorine or fluorine
with sodium, potassium, or calcium.
 Halite (NaCl) is the most common halide. Often referred to
as table salt.
Mineral Groups
6 Sulfides
 compounds consisting of an atomic structure of one
)
or more metals combined with sulfur.
 common ore mineral.
(FeS2), Galena (PbS), Sphalerite (ZnS).
Examples: Pyrite
7 Native Minerals
)  elements that occur uncombined in nature.
 commonly called native elements.
 Examples:
(Au), Silver (Ag), Copper (Cu), & Sulfur (S)
Gold