Transcript Minerals

Geology
Rocks, Minerals,
Volcanoes, & Earthquakes
Minerals
 Naturally occurring
 Inorganic solid ( not from living
matter)
 Has a definite structure; crystals
 Has a definite composition; a
compound or element.
Minerals
 Crystals =is a solid in which atoms are
arranged in repeating patterns.
 NaCl, table salt , forms a cubic crystal.
 Wulfenite forms a tetragonal crystal.
 Corundum = Hexagonal
 Gypsum = Monoclinic
 Topaz = Orthorhombic
Topaz
Mineral : How they form…
 1. Hot magma ( melted rock) cools to
form minerals.
 The types and amounts of elements
in the magma determines which
minerals form.
 2. Crystals form from minerals dissolved
in liquids.
 When the liquid evaporates, mineral
crystals are left behind.
How Minerals Form:
 3. Precipitation out of solution is the
third way.
Mineral Composition
 There are 90 elements that occur naturally;
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98% of the Earth’s crust is made of only eight
of these elements.
Oxygen is 46.6%
Silicon is 27.7%
Aluminum is 8.1%
Iron is 5%
Calcium is 3.6%
Sodium is 2.8%
Potassium is 2.6%
Magnesium is 2.1%
Mineral Groups
 There are about 4000 minerals.
 Most of the common minerals are in the
group called silicates.
 Silicates contain silicon, oxygen and
one or more other elements.
 Quartz and Feldspar are common
rock-forming minerals in the silicate
group.
Feldspar
Quartz
Mineral Groups
 Carbonates
 Oxides
 Sulfides
 Sulfates
 Halides
 Hydroxides
 Phosphates
Mineral Identification
 Appearance
 Hardness
 Luster
 Color
 Streak
 Fracture
 Cleavage
 Other Properties
Mineral Properties
 Appearance – Color and general
appearance can help to identify a
mineral.
 Many minerals look very similar.
 Many minerals are found in different
colors.
 Other properties must be used to
identify minerals.
Mineral Properties
 Hardness = The Mohs Scale of
Hardness measures how easily a
mineral can be scratched.
 Talc is the softest, a 1 on the scale.
 Diamonds are the hardest, a 10.
Talc
Mineral Properties: Hardness
 Mohs Scale
Mineral Properties:Luster
 Luster: how light is reflected from a
mineral’s surface.
 Metallic Luster = shines like metal
 Nonmetallic Luster = any mineral that
does not shine like metal.
 Nonmetallic can be : dull, pearly, or
silky.
Orthoclase
Galena
Luster
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Mineral Properties: Streak
 Streak is the color of the mineral when it
is broken up and powdered.
 The mineral is rubbed across a white,
unglazed, porcelain tile.
 Minerals harder than the streak plate (7)
will not have streak.
 Graphite (pure carbon) has streak on
paper. It is used in pencils, not lead.
Mineral Properties: Cleavage
and Fracture
 Minerals that break with rough or jagged
edges have fracture.
 Minerals that break along smooth , flat
surfaces have Cleavage.
 Some minerals have unique
properties;
 Magnetite is magnetic, Calcite fizzes
with HCl ( acid).
Mineral Properties: fracture
 21.Limestone = even
 22. Serpentine = uneven
 23. Obsidian = conchoidal
 24. Rose Quartz = sub-conchoidal
 25. Tremolite = splintery
 26. Copper = hackly
Types of Cleavage
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Mineral Properties: Cleavage
 15. Mica = Basal ( one direction)
 16. Feldspar = Pinacoidal ( two
directions)
 17. Amphibole = Prismatic ( Two
directions at 124o and 56o
Cleavage
 18. Halite = Cubic ( Three directions, at
right angles)
 19. Calcite = Rhombohedral ( Three
directions not at right angles.)
 20. Fluorite = Octahedral ( four
directions)
Uses of Minerals
Jewelry on the Web
 Gems are rare and beautiful minerals
which are cut and polished for jewelry.
 Differences between gems and
common minerals are small: Amethyst
is a gem form of quartz (SiO2) with
manganese traces. The Mn gives
amethyst its purple color.
Uses of Minerals
 Ores is a mineral that is useful, and can
be mined for profit.
 Bauxite is a mineral ore used to make
aluminum.
 Hematite is a mineral ore source for
iron.
Uses For minerals
Minerals in Your House(Web)
 Copper is used for coins, wires, pipes
and cooking tools.
 Ilmenite and rutile are mineral ores
which provide titanium. It is used for hip
replacements, bicycles, and airplane
parts
Science and Art
 Minerals are in paint pigments, crayons,
pastels, chalks, clays, and glazes.
 Cinnabar is used for red.
 Malachite and Azurite are used for
greens and blues.
By Salvador Dali
Science and Art
 Lapis Lazuli is used for dark blues.
 Ochre is used for yellows and reds
By Salvador Dali