Transcript Chapter 3:Minerals of the Earth`s Crust

Chapter 3:Minerals of the Earth’s Crust
Mineral-A naturally formed inorganic solid that has a
definite crystalline structure. Rocks are composed of
minerals. Contain one or more of 92 elements.
Element-A pure substance that cannot be broken down
into a simpler substance.
Native Element -A mineral that is composed of only
one element.
Compound-A substance composed of two or more
elements that have been chemically combined.
Minerals are classified by their chemical
composition
1.
2.
Silicate Minerals -minerals composed of silicon,
oxygen and other elements and make up 90% of the
Earth’s crust.
Nonsilicate Minerals -minerals that do not contain
silicon and oxygen.
a. Carbonates: contain carbon and oxygen.
b. Sulfides: contain one or more elements combined
with sulphur.
c. Sulfates: contain sulphur and oxygen in the form of
SO4.
d. Native Elements
e. Oxides: Contains elements combined with oxygen.
f. Halides: Compounds such as salt (NaCl) that are
used in industry.
Properties
• Are characteristics that describe a mineral such
as color, luster, streak, etc.
Color – The appearance of a mineral based upon the
contained impurities.
Luster - The manner in which a mineral’s surface
reflects light.
Streak – The color of the powdered mineral left behind
when rubbed against an unglazed porcelain tile.
Cleavage – The tendency of a mineral to break along
smooth, flat surfaces.
Fracture – The tendency of a mineral to break
unevenly along curved or irregular surfaces.
Properties (cont.)
Hardness – A mineral’s resistance to being scratched.
Density – The measure of the amount of matter in a given space;
the ratio of the mass to the volume. D=M/V.
Special Properties: Characteristics that are particular to only a few
types of minerals.
Fluorescence – Certain minerals will glow when viewed with an
ultraviolet light.
Magnetism – Some minerals are natural magnets. Ex. : Magnetite
a.k.a. loadstone.
Radioactivity – Some minerals can contain elements that give off
radiation. Ex. : Radium, Uranium.
The Formation of Minerals
• Evaporating Salt Water – as water evaporates,
minerals such as halite and gypsum are left behind.
• Surface & Groundwater – can carry dissolved minerals
into bodies of water where they crystallize to form new
minerals.
• Heat & Pressure – can change the chemistry of the
existing rocks to form metamorphic rocks.
• Hot Water Solutions – occur when ground water sinks
deeper to be heated by magma and react with minerals.
• Pegmatites – teardrop shaped bodies with large crystals
that form as magma moves upwards.
• Plutons – magma that moves upwards then cools to
form crystals.
Mining – The removal of rocks and minerals from
the Earth.
1.) Ore – A naturally occurring mineral that is
mined for profit.
2.) Surface Mining – Removing deposits that are
close to the surface in open pits or quarries.
3.) Subsurface Mining – Removing minerals that
are located very deep within the Earth.
a.) Reclamation – The process in which
the surface land is returned to it’s original, preexisting state after mining has been completed.
4.) Recycling – The reuse of mined products to
reduce our mineral needs.
Classes of Minerals
• Metallic Minerals – Minerals that have shiny
surfaces and are good conductors of heat and
electricity.
• Nonmetallic Minerals – Minerals that are
nonmetals, dull and are electrical insulators.
• Gemstones – A type on nonmetallic mineral that
is highly valued for it’s beauty and rarity. The
color of a gemstone is it’s most important and
attractive characteristic.
• Caret – A unit of mass for a gemstone.
1 caret= 200mg.