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Atoms
Atoms
–
basic building blocks for all earth
materials; consist of 3 basic components:
protons, neutrons, electrons
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Atoms combine to form
Elements
Elements
–
fundamental component that
can not be broken down into other
substances by ordinary chemical
processes
Elements combine to form minerals
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General Facts About Minerals
2,000 + minerals have been identified
A few are “native elements”
--
made of
only one element, such as sulfur, gold.
copper, and graphite (carbon)
Most are compounds, especially the
silicate group (Si, O).
Other important groups are oxides,
carbonates, and sulfides.
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Mineral Criteria
1. Crys tal l ine so l id
–
atoms have speci f ic
arrangement or c rys tal st ruc ture
2. Natu ral ly occurr ing
–
no t manufactured
3. Have a def in i te chemical compos i tion
–
may be a sing le element o r combinat ion
4. Inorganic
–
minerals not made by l iv ing
th ings (org anic )
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MINERAL FORMATION
CRYSTALLIZE FROM MAGMA or LAVA
solidification of liquid magma/lava to solid
with a definite internal arrangement of
atoms into a regular repeating pattern
PRECIPITATE FROM SOLUTION
dissolved minerals come out of solution
(water) to form solids
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Physical Properties of Minerals
1- Optical PropertiesColor
Streak
Luster
Diaphaneity
2- Cohesive Properties
Hardness
CleavageParting
Fracture
Tenacity
3- Sense Properties
Touch
Odour
Teste
4- Specific Gravity
5- Other Properties such as:
Magnetism
Electricity
Radioactivity
FusibilitySolubility
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Minerals are identified by their
Physical Properties
Crystal Form – determines physical properties
Color
Streak
Luster – metallic, non-metallic
Hardness – Mohs Hardness Scale (1-10)
Cleavage
Fracture
Acid Test for carbonate minerals
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A mineral’s physical properties
are controlled by its internal
arrangement of atomsregularly repeating, orderly pattern
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The most common crystalline
structure
Silica-oxygen tetrahedron – basic
building block for silicate minerals
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Silica tetrahedron combine
several different ways
Five major types of
silicate minerals
based on their
structure A) Isolated tetrahedron
B) Single chain
C) Double chainsD) Sheet silicates
E) 3-D framework
silicates
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Minerals can have the same chemical composition
(Carbon) but different physical properties because
of their crystal structure
Diamond Graphite
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COLOR
Color is not usually a definitive property of
a mineral.
Some minerals have characteristics colors
Others vary due to chemical differences or
impurities (atoms mixed inside the main
elements)
However most minerals have a variety of
colors.
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Some Colors of Quartz
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Varieties of Hematite – all same color streak
HARDNESS
Mi l’ i t t
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HARDNESS – Mineral’s resistance to
scratching or abrasion. Minerals with higher
numbers will scratch minerals below
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LUSTER – Does this look like it could
be made from a hard metal?
Describes how light reflects off the surface
Categories: Metallic or Non-metallic
Metallic – luster of metal – shines like a hard metal
(light does not penetrate)
Many non-metallic minerals are SHINY because theyare transparent or semi-transparent
Non-metallic: vitreous or glassy; silky; pearly; greasy; waxy,dull; earthy
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Examples of metallic luster
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Pyrite (FeS2)
Galena (PbS)
More Examples of Metallic Luster
PYRITE
GALENA
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Example of non-metallic luster
Vitreous--quartz
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Example of non-metallic luster
Silky--example plagioclase feldspar
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Non-metallic and metallic luster –
earthy hematite – metallic hematite
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Cleavage and Fracture
Some minerals split along flat surfaces(called cleavage planes) when struck
hard--this is called mineral cleavage Other minerals break unevenly along
rough or curved surfaces--this is calledfracture
A few minerals have both cleavage andfracture ( mica )
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FLUORITE
HALITE
Halite (NaCl)
Fluorite (CaF2)
Cleavage – due to weak bonds in
the crystal structure
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Cleavage
BIOTITEMUSCOVITE
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Rose Quartz – Conchoidal Fracture
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Conchoidal Fracture - Quartz
Obsidian
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Acid Test for Carbonates
Special Characteristics:
Carbonates react with dilute HCl and other
acids by fizzing or bubbling (releasing
CO2 gas)
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Common uses include: Use back
page of ESRT for this information
Aluminum--packaging, transport, building
Beryllium--gemstones, fluorescent lights
Copper --electric cables, wires, switches
Feldspar --glass and ceramics
Iron--buildings, automobiles, magnets
Calcite--toothpaste, construction