2.2 Minerals
Textbook, pp 44 - 49
Minerals
• A mineral is…..naturally occurring.
A mineral forms by natural
geologic processes.
• A mineral is… a solid substance.
Minerals are solids within the temperature
ranges that are normal for Earth’s surface.
A mineral has... an orderly crystalline structure.
Minerals have their atoms arranged in an
orderly and repetitive manner.
A mineral has… a definite chemical composition.
Most minerals are chemical compounds made
of two or more elements.
• A mineral is… generally considered inorganic.
Minerals are not generally produced
by living creatures.
• (An exception to the “inorganic” rule is
calcium carbonate, which many marine
animals secrete to build their shells.)
Quick Question
• Can you name three things in this
room made from the mineral quartz
that was ground up, melted and
then cooled?
How Minerals Form –
Four Major Processes
1.
Crystallization from magma.
•
When magma cools, elements combine to
form minerals.
Quartz
Horneblende
2. Precipitation
• When water evaporates, some of the dissolved
substances can react to form minerals. Minerals
are left behind, or precipitated, out of the water.
Halite
Calcite
3. Pressure and Temperature
• Some minerals form when existing minerals
are subjected to changes in pressure and
temperature. Their atoms are “re-arranged”
by pressure, or are re-stabilized into new
minerals by heat.
Talc
Muscovite
4. Hydrothermal Solutions
• A hydrothermal solution is a very hot mixture
of water (100°C to 300°C) and dissolved
substances. When these solutions come into
contact with existing minerals, chemical
reactions take place to form new minerals.
Bornite
Chalcopyrite
Quick Question
• What is the official mineral for the state of
California?
GOLD
Mineral Groups
• Over 3,800 minerals have been named, and
several new ones are identified each year.
Common minerals, together with the thousand
of others that form on Earth, can be classified
into groups based on their composition.
Jasper and Agate Pebbles, Oregon Coast
http://gingerbreadsnowflakes.
com/archive/200901
Silicates
• The two most
abundant elements
in Earth’s crust are
silicon and oxygen.
Quartz, the most
common mineral.
• Silicon and oxygen combine to form a
structure called the silicon-oxygen
tetrahedron.
Basic Crystal Shapes
• Silicon-oxygen tetrahedra can join in a variety
of ways. The silicon-oxygen bonds are very
strong.
Carbonates
• Carbonates are minerals that contain the
elements carbon, oxygen and one or more
other metallic elements.
• Calcite is the most common carbonate
mineral.
Oxides
Corundum (ruby) is
aluminum oxide.
• Oxides are
minerals that
contain oxygen
and one or more
other elements,
which are
usually metals.
Sulfates and Sulfides
• Sulfates and Sulfides are minerals that
contain the element sulfur. Sulfates form
when mineral-rich waters evaporate.
Pyrite
(Fool’s Gold)
Halides
• Halides are minerals that contain a halogen
ion plus one or more other elements.
Halite
(Rock Salt)
Native Elements
• Native elements are a group of minerals that
exist in relatively pure form.
Sulfur
Silver