CHEMICAL COMPOSITION OF THE EARTH CRUST MINERALS AND ROCKS

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CHEMICAL
COMPOSITION
OF THE
EARTH CRUST
MINERALS
AND
ROCKS
COMMON ELEMENTS EARTH’S CRUST
GRANITE MINERALS
BIOTITE QUARTZ
MICA
PLAGIOCLSE
FELDSPAR

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MINERALS
 What is a Mineral?
1. Solid
2. Naturally Occurring
3. Inorganic
4. Fixed Chemical Formula
5. Specific Atomic Arrangement
 Crystalline in nature, displaying consistent
geometric shapes
 Grouped into: Silicates, Oxides and Carbonates
 Also, metallic and non-metallic minerals
COAL
TALC GYPSUM

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FLORIDE SULFUR
GRAPHITE DIAMOND

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MINERALS MINERALS
 Physical properties of Minerals
 Colors
 Shape
 Texture
 Smell
 Taste
 Appearance and
 Hardness because of;
 Mineral’s internal arrangement of atoms
 Sulfur appears yellow with a smell of rotten
eggs because of internal arrangement of atoms
 Halite is salty because of atoms arrangement
DIAMOND GRAPHITE

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 What is a Rock?
 Rock is an aggregate of mineral particles – but may
also contain organic materials
 Minerals are essentially the building blocks of rocks
 Bedrock → Outcrop → Regolith → Soils
ROCKS ROCK TYPES
 Igneous Rocks
 Form due to cooling
and crystallization of
magma
 Sedimentary Rocks
 Form through
lithification of
sediments from
other rocks
 Metamorphic Rocks
 Bu recrystallization
of other rocks due to
heat, pressure, and
chemical alteration
IGNEOUS ROCKS
Igneous Rocks are divided into Two Classes:
 Volcanic (Extrusive) Igneous Rocks
 Volcanic extrusive igneous rocks form on earth's
surface as lava cools
 Basalt; Basalt is most widespread volcanic rock
o It is a dark, fine-grained rock
o Basalt is the rock of the sea floor
 Plutonic (or Intrusive) Igneous Rocks
 Plutonic igneous rocks form deep underground where
magma cools slowly; these rocks have a coarse
crystalline texture
 Granite
o Granite most widespread of plutonic igneous rocks
o It underlies much of the continental crust.
IGNEOUS ROCKS

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SEDIENTARY ROCKS
 Most sedimentary rocks are formed of layers of
materials that have washed into lakes, rivers and
oceans –
 Sedimentary rocks form strata
 Often layers are tilted by earth movements
 Sedimentary rocks contain fossils
 How do sediments turn into hard rock?
 Through Lithification Processes:
 Compaction
 Cementation
 Crystallization
SUBCLASSES OF SEDIENTARY ROCKS
 Clastic:
 Form from bits and pieces of other rocks
 Chemical:
 Consist of minerals deposited from a solution
 Organic:
 Consist of organic matter such as plants and
animal remains
 Organically-formed sedimentary rocks:
From the remains of plants and animals (fossil
limestone, coal)
COMPOSITION OF SEDIENTARY ROCKS METAMORPHIC ROCKS
Rocks that have been changed in form due to heat,
pressure and chemical alteration.
FOLIATED; Slate, Schist, Gneiss
NONFOLIATED; Marble, Quartzite
 Slate: forms when shale is compressed by heat and
pressure; splits easily
 Schist: dominated by platy or needle-like minerals that
form shiny layers
 Gneiss: under pressure the minerals in granite
recrystallize to form bands of light and dark minerals
 Marble: Limestone recrystallizes into marble – a
denser and more crystalline form of calcite
 Quartzite: Sandstone changes into quartzite; Sand
grains recrystallize to form a hard mass of quartz

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METAMORPHIC ROCKS
HOW ROCKS RECYCLE ?
 The rock cycle is a general model that describes how
various geological processes create, modify, and
influence rocks
 The origin of all rocks can be ultimately traced back
to the solidification of molten magma
 Magma consists of a partially melted mixture of
elements and compounds commonly found in rocks
 Magma exists just beneath the solid crust of the
Earth in an interior zone, the mantle
 The Rock Cycle shows how rocks of any rock class
can be recycled into rocks of any other rock class.
ROCK
CYCLE STAGES IN ROCK CYCLE
 Rocks physically and chemically decomposed by
many surface processes known as weathering
 The debris transported by erosional processes via
streams, glaciers, wind, and gravity
 When debris is deposited as permanent sediment,
the processes of burial, compression, and chemical
alteration over time produce sedimentary rocks

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STAGES IN ROCK CYCLE
 Geologic processes like tectonic folding and
faulting exert heat and pressure on both igneous
and sedimentary rocks, altering them physically or
chemically – rocks modified in to metamorphic-
rocks
 Rock eventually returned to Earth's interior by
tectonic forces at areas known as subduction zones
 Once in Earth's interior, pressures and
temperatures melt the rock into magma to begin
rock cycle again