Download rocks and minerals!

Science
ROCKS!!!
Geology Rocks!
ROCKS AND MINERALS!
Earth’s Resources
Focus Question:
What properties make an Earth resource important?
• Earth resources have properties that make them
important and useful.
•Properties that determine the usefulness of an ore
or mineral may be identified using a chart, diagram
or dichotomous key.
Minerals!
• Natural, solid materials found on Earth that are
the building blocks of rock; each has a certain
chemical makeup and set of properties that
determine their use and value.
Minerals
continued…
• Mineral are homogeneous, meaning the
same all the way through
• Minerals can be called a “Earth material”
• These naturally occurring homogeneous
substances (such as stone, coal, salt, sulfur,
sand, tin, iron and zinc) are usually obtained
from the ground.
• There are about 4,000 known minerals on
Earth
Minerals are
not made by
people; they
are …
…naturally occurring substances.
But since they were never living
we call them inorganic.
Examples of Minerals
Quartz
Calcite
Iron
Hematite
Diamond
Uses of Minerals
Quartz makes
glass.
Diamonds make
jewelry.
Many things that we
see and use every day
are made from iron.
Physical Properties
•
•
•
•
•
•
Density
Luster
Color
Streak
Texture
Hardness (Moh’s Scale)
Density (or Specific Gravity) is a very
important property of minerals. The
calculation is fairly simple - weight/volume.
Which property means
the way the light bounces
off the mineral?
What words can be used to
describe a mineral’s luster?
•Metallic (shiny like a metal)
•Shiny (like a diamond)
•Glassy
•Resinous (looks like sap, gum, pitch, or tar)
•Pearly
•Oily or greasy
•Silky (appears to have fibers like a woven fabric)
Why is color not the best property to
use to identify a mineral?
slate
limestone
Many minerals have
the same color.
Streak
• Streak color: Use the
back of a bathroom tile
as a streak plate. Rub
the mineral across it
and examine the color
of the streak.
Hardness: What are three testers
that can be used to determine a
mineral’s hardness?
fingernail, penny, nail
Moh’s Hardness Scale
• This scale is relative. You assign a number to a mineral
by seeing what scratches what. To get the range of
hardness for a sample do this: Try scratching it with your
fingernail. If you can, the Moh’s scale hardness value is
2.5 or less.
• Try scratching with a penny. If you can, the value is 3.5
or less.
• Try scratching with a steel nail. If you can, the value is
5.5 or less.
• See whether the mineral will scratch glass. If it will, the
Moh’s value is 6 or more.
Moh’s Hardness Scale
Can you scratch it with your fingernail?
• If you can, it is 2.5 or less.
• If you CAN NOT, it is higher than 2.5… go on to penny.
Can you scratch it with a penny?
• If you can, the value is 3.5 or less.
• If you CAN NOT, it is higher than 3.5… go on to steel nail.
Can you scratch it with a steel nail?
• If you can, the value is 5.5 or less.
• If you CAN NOT, it is higher than 5.5…
Your fingernail has a
hardness of 2.5 on the
Mohs scale. If you can
scratch a mineral with
your fingernail, it must be
softer than 2.5. If you
can't scratch it, it must
be harder than 2.5.
A pocket knife has a
hardness of 5.5 on the
Mohs scale. If your knife
can scratch a mineral, it
must be softer than 5.5.
If it can't, then it must be
harder than 5.5.
Moh’s Hardness Scale
Dichotomous Key
• A dichotomous key is a tool that allows the
user to determine the identity of items in the
natural world, such rocks, and minerals, based
upon their properties.
• The keys consist of a series of choices that lead
the user to the correct name of a given item.
• "Dichotomous" means "divided into two
parts". Therefore, dichotomous keys always
give two choices in each step.
Time to
practice
identifying
minerals!
Minerals and RocksWhat is the difference?
Rocks are made of one or
more minerals
All rocks are made of 1 or more
mineral, but minerals are not
made of rocks.
What are rocks?
Rocks are made of minerals. Some
rocks are made of just one, while
others are made of many.
Rock Words: There are many common names for rocks and the usually
give you an idea of how big the rock is. Here are a few:
mountain - huge, giant hunk of rock that is still attached to the earth's
crust, doesn't move, tall
boulder - large, taller than a person
rock - large, you could get your arms around it or a bit smaller but it is
usually jagged, broken off a bigger piece of rock
river rock - round rocks that are along the edge & at the bottom of fastflowing rivers
stone - medium, you could hold it in two hands
pebble - small, you can hold it with two fingers, could get stuck in your
shoe, usually rounded
sand - made up of tiny pieces of rock, grains of sand
grain - tiny, like a grain of rice or smaller, often found on a beach
dust - really fine powder that is mixed in with sand or soil
speck - as in a speck of dirt
How Rocks Form
Flowing water, exploding volcanoes,
and heat and pressure from inside the
Earth all form the three types of
rocks.
Uses of Rocks
• Building
• Machines & Tools
• Consumables & Processes
• Decorations
• Jewelry
• Statues
• Electricity and heat
The Three Types of Rocks
Igneous Rock
Sedimentary Rock
Metamorphic Rock
Igneous
Rock
Igneous Rocks are formed from the cooling of
magma which comes from volcanoes. Some magma
cools below the surface of the earth to form hard
rocks like granite. Some magna cools above the
earth to form light rocks like basalt.
Igneous rocks are called fire rocks and are formed
either underground or above ground.
Underground, they are formed when the melted
rock, called magma, deep within the earth becomes
trapped in small pockets. As these pockets of
magma cool slowly underground, the magma
becomes igneous rocks.
Igneous rocks are also formed when volcanoes
erupt, causing the magma to rise above the earth's
surface. When magma appears above the earth, it
is called lava. Igneous rocks are formed as the lava
cools above ground.
Melted rock below the
Earth’s surface is called…
Melted rock above the
Earth’s surface is called…
The breaking down and
wearing away of rocks is
called…
Small bits and pieces
of rocks are called…
The movement of
sediments from one place
to another is called…
Sedimentary Rocks are
formed on the earth's
surface. Sedimentary
rocks are made from
broken rocks and
minerals. They can,
also, be made from
hardened plants and
animals.
Deposition
Deposition is the settling of sand and
sediment. (ex. settles to bottom of sea)
Sedimentary Rocks
Sedimentary rocks are formed in three steps:
•Layers of sediment are deposited at the
bottom of seas and lakes.
•Over millions of years the layers get
squashed by the layers above.
•The salts that are present in the layers of
sediment start to crystallize out as the water
is squeezed out. These salts help to cement
the particles together.
Compaction:
happens when sediments are deeply buried, placing
them under pressure because of the weight of overlying
layers. This squashes the grains together more tightly.
Cementation:
is where new minerals stick the grains together – just as
cement (from a bag) binds sand grains in a bricklayer’s
mortar.
Example: Conglomerate is a type of
rocks that forms this way
Metamorphic Rocks are rocks
which have been changed by
temperature and/or
pressure. Metamorphic rocks are
"morphed" or changed below the
earth's surface. Sedimentary and
igneous rocks can become
metamorphic rocks.
What is any trace,
mark, or remains of
an organism called?
How old must a fossil be?
Now
that’s
old!!
10,000
years
What kind of rock
are fossils usually
preserved in?
They study
Why do
them to
scientists
learn about
study fossils? extinct
plants and
animals.
Homework: Due Thursday
1. Find a rock.
2. Write a paragraph explaining what type
of rock you think it is (igneous,
metamorphic, sedimentary) and why you
don’t think it is one of the other two
types.
3. Bring in the rock (or a picture if it is too
large to bring in) to share Thursday.
The Rock Cycle
The Earth is active. As you are reading this:
•Volcanoes are erupting
and earthquakes are shaking;
•Mountains are being pushed up and are
being worn down;
•Rivers are carrying sand and mud to the
sea;
•Huge slabs of the Earth's surface
called tectonic plates are slowly moving about as fast as your fingernails grow.
OK, so maybe
it gets a little
more
complicated…
http://www.learner.org/i
nteractives/rockcycle/di
agram.html