MINERALS
WHAT ARE MINERALS AND HOW DO
THEY FORM?
MATTER AND MINERALS
1. An atom is the smallest part of an element that retains the elements'
properties.
2. Compounds are substances that are made up of two or more elements that
are chemically bonded as molecules.
3. Minerals are solids and are composed of elements.
WHAT DO MINERALS HAVE IN COMMON?
• A mineral is a naturally occurring, inorganic solid
that has a definite crystalline structure and
chemical composition.
• Minerals are grouped according to the shape of
their chystals.
EXAMPLES OF MINERALS
THE MINERAL AMETHYSTChemical Formula SiO2
Composition : Silicon dioxide. Its purple
coloring is usually caused by impurities
of iron or manganese compounds.
Color Light to dark purple. Sometimes
banded with purple and whitish lines.
May also be mixed together with Citrine.
StreakWhite
Hardness7
INORGANIC AND NATURALLY OCCURRING
• AN inorganic substance is not made up of living things or the remains of living
things.
• Minerals are formed by many different natural processes that occur on Earth
and throughout the universe.
• Talc – used in baby powered: is formed deep in Earth as high temperature
and pressure change the rock.
CRYSTALLINE STRUCTURE
Minerals are composed of crystals:
A crystal is a sold, geometric form that results from a repeating patter of
atoms or molecules. Turn to page 142 and 143 in textbook.
CRYSTALS SHAPE
• A crystals shape is produced by the arrangement of the
atoms or the molecules within the crystal. The
arrangement is determined by the kinds of atoms or
molecules that make up the mineral.
MINERALS CAN FORM THREE WAYS
• 1. Magma and lava cooling
• 2.Metamorphism
• 3. From Solutions
MINERALS FORMED FROM MAGMA OR LAVE
• Magma and lava contains atoms present in
minerals, when magma and lava cool quickly and
solidify small crystals form.
• When cooled slowly large crystals are formed
• What is the difference between magma and lava?
QUARTZ
Quarts is one of the minerals that crystallize from magma
and lava.
MINERALS FORMED FROM COOLING MAGMA OR
LAVA
• Topaz:
Magma that cools forms Pegmatites . Crystals in
Pegmatites are found in Topaz.
METAMORPHISM
• Temperature and pressure can cause atoms to
break bonds with other atoms creating new
minerals.
METAMORPHISM
Graphite composed entirely of carbon atoms
transfers into a diamond under head and
pressure.
SOLUTIONS
• Minerals form from solutions by the water
evaporating. As water evaporates, the substances
form into a solid.
• Ex: gypsum forms as water evaporates: the mineral
gypsum is left after water evaporate hardens and
gypsum is formed.
HOW MINERALS ARE CLASSIFIED
• Based on chemical composition
• Divided into two groups: Silicate minerals and nonsilicate minerals
Feldspar
Quartz
SILICATE MINERALS
• Silicate minerals make up 90% of the Earth’s crust.
• Minerals with silicon and oxygen are called silicate
minerals.
• Silicates are made up of repeating tetrahedron shaped
units.
SILICON TETRAHEDRONS
One Silicate tetrahedrons are made of one silicon
atom bonded into four oxygen atoms
Most silicate minerals are composed of silicate
tetrahedrons combined with other elements like
aluminum pg. 146
NONSILICATE MINERALS
• Do not contain silicate tetrahedron building block
• These minerals are made up of elements : carbon, oxygen,
fluorine, iron and sulfur.
PROSPERITIES TO IDENTIFY MINERALS
• Color – Color can be used to identify a mineral.
• Streak – the mark left by the mineral on a white tile is the mineral’s
streak. Streak is more reliable in detecting a mineral than its color.
• Luster- When the mineral gives off a shine. Two types of luster
metallic and nonmetallic
• Cleavage: has a smooth surface and parallel cracks running through
the mineral. Book pg. 149
• Fracture: uneven breaks throughout the mineral.
PROPERTIES TO IDENTIFY MINERALS
• Density – how much matter in the substance. The density of the
mineral pyrite can distinguish it form gold.
• Hardness – a mineral’s resistance to being scratched is its harness.
Scientists use Mohs scale to rate the minerals degree of hardness. Pg.
150
• If the reference mineral scratches your mineral, the reference mineral
is as hard or harder than your mineral. What is the hardest known
mineral and only the same mineral can scratch it?