Download Rocks: Mineral mixtures

Rocks: Mineral
mixtures
Rocks

Rock – A solid mixture
of one or more
minerals.
The Rock Cycle

The process by which one rock type changes into
another. http://www.learner.org/interactives/rockcycle/
Sedimentary Rocks

Rocks that form when sediments are
compacted and cemented together.
Metamorphic Rocks

Rocks that forms
when the texture
and composition of
a preexisting rock
changes by heat
and pressure
produced deep
within the Earth.
Igneous Rocks

Rocks that form from cooling of
magma and lava both inside and on
the surface of the Earth.
Composition

The minerals a rock is made of determines
its composition.
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Example – Granite typically has 10% Biotitie
Mica, 35% Quartz and 55% Feldspar.
However, there are classifications of Granites
that have different amounts of each of these
minerals.
Composition cont.
Texture

The texture of a rock is determined by the
sizes, shapes and positions of the grains
which it is made of.
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Fine grained – silt or clay particles
Medium Grained – sand
Coarse Grained - pebbles
Fine Grained
Fine grained siltstone
Medium Grained
Medium grained Sandstone
Coarse Grained
Coarse Grained Conglomerate
Igneous Rocks

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Rocks formed when magma and lava
solidify
Igneous comes from the Latin word for
“fire”.
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Intrusive – igneous rocks from when magma
cools below the Earth’s surface.
Extrusive – igneous rocks that form from lava
cooling on the surface of the Earth

Intrusive, or plutonic, igneous rocks form
when magma cools slowly below the
Earth's surface. Most intrusive rocks have
large, well-formed crystals. Examples
include granite, gabbro, and diorite.
Granite
Gabbro
Diorite

Extrusive igneous rocks form when
magma reaches the Earth's surface
cooling quickly to form lava. Most
extrusive (volcanic) rocks have small
crystals. Examples include basalt, rhyolite,
and andesite.
Basalt
Rhyolite
Andesite
Mafic Rocks

Mafic is used for silicate minerals,
magmas, and rocks which are relatively
high in the heavier elements. The term is
derived from using the MA from
magnesium and the FIC from the Latin
word for iron. Mafic minerals are usually
dark in color and have relatively high
specific gravities
Felsic Rocks

Felsic, is used for silicate minerals,
magmas, and rocks which have a lower
percentage of the heavier elements, and
are correspondingly enriched in the lighter
elements, such as silica and oxygen,
aluminum, and potassium. The term
comes from FEL for feldspar and SIC,
which indicates the higher percentage of
silica.

Intrusive
igneous rocks
are dense and
hard and
withstand
weathering
and erosion
well.
Sedimentary rock Formation

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Sedimentary rock – grains of sand and
sediment are eroded by weathering
forming thick layers that are eventually
cemented together.
They are commonly formed on the ocean
floor and other low areas.
The most common rock found on the
Earth’s surface
Weathering
Deposition
Forming the ocean floor

Limestone rocks are
sedimentary rocks
that are made from
the mineral calcite
which came from the
beds of evaporated
seas and lakes and
from sea animal
shells. This rock is
used in concrete and
is an excellent
building stone for
humid regions.

Conglomerate rocks
are sedimentary rocks.
They are made up of
large sediments like
sand and pebbles. The
sediment is so large
that pressure alone
cannot hold the rock
together; it is also
cemented together with
dissolved minerals.
Grand Canyon
Painted Desert
Metamorphic Rocks
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Metamorphic rocks are formed deep within
the Earth.
“Meta” in Latin means change. “Morph” in
Latin means shape.
Thus, metamorphic means a physical
change to a rock caused by heat and
pressure.
Contact Metamorphism

When surrounding
rock comes in
contact with
magma but does
not melt they
often change to
harder
metamorphic type
rocks.

The lava flow exposed in this road cut
near Alturas, California, has baked the
mud beneath it into brick-red shale, a case
of contact metamorphism.
Regional Metamorphism

Rocks that are typically
altered in composition,
texture, or internal
structure by extreme
heat and pressure over a
large area during
mountain formations or
subduction.
Foliated Metamorphic Rocks
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The generally-crude layering or foliation
of many metamorphic rocks is due to the
intense directional pressure they
experience
Usually along a convergent plate tectonic
boundary.
Flat mineral crystals and fragments
gradually become oriented perpendicular
to the directions of pressure.
Foliated rocks
More Foliated rocks

jaspilite, which
consists of
alternating bands
of red chert
(jasper;
cryptocrystalline
quartz - SiO2),
red hematite (iron
oxide - Fe2O3),
and silvery-gray
specular hematite
(iron oxide Fe2O3).
Chert