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Rocks!
The Earth’s Crust
Rocks
All the rocks you see around you are made
up of different minerals
Imagine a rock as a chocolate chip cookie,
what does the cookie contain?
Flour, butter, sugar, chocolate chips
A rock contains different ingredients, they
are called minerals. There are about 3000
minerals in the world.
3 Types of Rocks
There are 3 main types of rocks
Igneous
Sedimentary
Metamorphic
Igneous Rocks
Igneous means made from fire or heat.
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When volcanoes erupt and the liquid rock
comes up to the earth's surface, then new
igneous rock is made.
The texture of igneous rocks is very useful in
identifying unknown rocks.
Igneous rocks with large crystals (crystals
seen with the naked eye) are termed
phaneritic and are intrusive.
Phaneritic: Slow cooling of magma or lava
allows larger crystals to form.
Intrusive: The cooling of magma deep in the
Earth
 Igneous rocks with small crystals (crystals
Granite
that cannot be seen with the nakedeye) are
termed aphanitic and are extrusive.
aphanitic: Rapid cooling of magma or lava
produces very small crystals or a glassy
surface
extrusive: When magma reaches the Earth's
surface in a volcano and cools quickly
Sedimentary Rocks
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Are composed of particles derived from
pre-existing rocks or by the crystallization
of minerals that were held in solutions.
These rocks form in layers or strata.
Sedimentary Rocks
 3 important factors:
1. Clastic- rocks containing particles from
pre-existing rocks.
2. Organic- rock is made from shells or
other fossil fragments.
3. Chemical- indicates the minerals were
produced by chemical precipitation.
http://study.com/academy/lesson/detritalchemical-sedimentary-rocks-definitiondifferences.html
Metamorphic Rocks
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Metamorphic rocks are ones that have
changed.
‘Meta’ and ‘morph’ both mean change in
Greek
All metamorphic rocks would once have
been igneous or sedimentary.
What do you think made them change?
Metamorphic Rocks
Have foliated or non-foliated textures.
•Foliated- contain parallel planes of platy
minerals.
•Non-foliated-do not contain any parallel
planes, but do exhibit alterations such as
textural changes due to obliteration of
mineral grains.
Rocks and their uses
Rocks are very useful, can you think what
they are used for?
Fireplaces, roofs, worktops, tables, walls,
sharpening knives, headstones,
ornaments, pathways, jewellery, drawing,
scrubbing feet!
 What are the properties of rocks?
 Do they all have the same properties?
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Beautiful Rocks!

People like to wear rocks as jewellery and
decorate their homes with rocks.
Can you think of examples of these rocks?
Semi-precious stones
Other words for Rocks
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We sometimes call rocks pebbles, boulders,
stones, crystals or gemstones.
A boulder is a large rock
A pebble is a small rock that has been rounded
by wind or water.
Stones are larger than pebbles.
Crystals and gemstones are rocks made of just
one mineral. E.g a diamond is made of carbon.