Download Materials On The Earth`s Crust

UNIT 1 – MATERIALS ON THE EARTH
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MATERIALS ON THE EARTH’S CRUST
The Earth crust is the outer layer of our planet. It covers
the whole Earth surface. The thickness of this layer varies
from 6 to 12 Km on the seabed to up 60 Km in the great
mountain ranges.
The Earth crust is made up of rocks which in turn are
made up of minerals. There are many different types of
minerals. Diamond rings, talcum powder, and aluminum
foil are made from minerals. Copper wire, china dishes,
and table salt are also made from minerals.
What do all minerals have in common?
http://geology.about.com/od/mineral_ident/ss/beginmini
dent_4.htm
Minerals are solid materials of Earth’s crust. Minerals are
made of chemical elements. Some minerals are made of
one element (atom). Each kind of atom is represented by
a symbol. Gold (Au), silver (Ag), copper (Cu), and
carbon(C) are minerals made of one element.
Most minerals are chemical compounds. Chemical
compounds are two or more elements joined together
(molecules). Each mineral has chemical composition.
Scientists classify minerals by their chemical composition.
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UNIT 1 – MATERIALS ON THE EARTH
ACTIVITY
- Read the text and make a graphic bar about the three
most abundant elements in the universe and in the Earth.
The most abundant element in the universe is hydrogen
(H), which makes up about 3/4 of all matter! Helium (He)
makes up most of the remaining 24%. Oxygen (O) is the
third most abundant element in the universe. All of the
other elements are relatively rare.
The chemical composition of the Earth is quite a bit
different from that of the universe. The most abundant
element in the Earth's crust is oxygen (O), making up
46.6% of the Earth's mass. Silicon (Si) is the second
most abundant element (27.7%), followed by
aluminum(Al) (8.1%), iron(Fe) (5.0%), calcium(Ca)
(3.6%), sodium(Na) (2.8%), potassium(K) (2.6%). and
magnesium(Mg) (2.1%). These eight elements account
for approximately 98.5% of the total mass of the Earth's
crust.
Find out the four most abundant elements in living
things. Which are the same and which are different from
the most abundant elements in universe and in Earth
crust?
GRAPHIC BAR
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UNIT 1 – MATERIALS ON THE EARTH
Atoms and molecules make patterns when minerals form.
These patterns cause minerals to make shapes called
crystals. When minerals have time and space they can
grow into beautiful forms or shapes.
Diamond crystal structure
Hexagonal crystal
Some words to describe different crystal shapes are:
 cubic : equal, square faces
 dendritic : branching, tree-like, looks like the
veins in a leaf or like a painted “tree shape”
 dog-tooth : shaped like the canine tooth, like a
dog's tooth
 fibrous : looks like fibers, threads, parallel lines
 geode : spherical, round shape that is hollow
inside, often lined with crystals
 prismatic: like a prism with flat ends, longer than
it is wide.
 rose shaped : looks like a flattened flower or rose
with petals
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UNIT 1 – MATERIALS ON THE EARTH
ACTIVITY
Find out the composition of graphite and diamond.
Explain why they have different properties.
ACTIVITY
Are the following minerals? Give reasons for your answer.
a) Water
b) Zirconia (artificial diamond)
c) Coral
a)
b)
c)
………………… (is/is not) a mineral because it
…………………
ACTIVITY (make questions)
Put the words in the right order to make interrogative
sentences:
a) living things/formed by/minerals/Are?
b) the same/ Does/ chemical composition/ always/
have/a mineral?
c) have / How many/does/elements/gold?
d) minerals/to grow/What/into crystals/do/need?
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UNIT 1 – MATERIALS ON THE EARTH
PROPERTIES OF MINERALS
 Colour
Colour is one of the physical properties most commonly
used to describe minerals, but it is not a very good
property to use to identify minerals.
Some minerals are nearly always the same color like
azurite (blue) and sulfur (yellow) but many minerals
come in a variety of colors – the changes are caused by
slight chemical impurities or through exposure to heat,
moisture and air.
Some minerals have common names to describe a
specimen with a certain colour.
eg. Quartz – rock crystal (colorless), smoky quartz
(brown), citrine (yellow), amethyst (violet),
rose quartz (pink).
 Lustre
Lustre describes the way light reflects off of the surface of
a mineral. We can describe it as metallic (very shinny like
metals such as pyrite, gold or silver) or non-metallic.
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UNIT 1 – MATERIALS ON THE EARTH
!!! There are different words to describe non-metallic
luster: dull/earthy, waxy (like the surface of a candle),
greasy /oil, pearly, silky (like a piece of cloth),
glassy/vitreous (looks like a glass), resinous, adamantine
(like a diamond).
 Streak
If you rub a mineral against a streak plate you will get a
powder. The color of this powder is called streak. A
mineral can come in different colors but its strake is
always the same. A mineral’s strake may be different
from its outer colour. Pyrite looks like gold from the
outside but it has a green strake.
 Hardness
Hardness is how difficult is to scratch a mineral. Soft
minerals are easily scratched. Mohs scale of hardness
shows how hard a mineral is. Talc is number 1.It is the
softest. Diamond is number 10.It is the hardest. Every
item on the list can scratch something above it.
Scratching tools:
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UNIT 1 – MATERIALS ON THE EARTH






fingernail (2.2)
copper penny (3.5)
pocket knife (5.2)
piece of glass (5.5)
steel file (7.5)
piece of corundum (9)
Rating
1 Very Soft
2 Soft
3 Soft
4 Semi-Hard
5 Hard
6 Hard
7 Very Hard
Description
Can be scratched
with a fingernail
Can be scratched
with a fingernail
Can be scratched
with a copper penny
Can be scratched
with a common nail
Can be scratched
with a common nail
(5.2).
Mineral of hardness
6 or more will
scratch glass.
Can be scratched
with a concrete nail
8 Very Hard
9 Extremely Hard
10 The Hardest
Mineral Example
Talc
Gypsum
Calcite
Fluorite
Apatite
Feldspar
Quartz
Topaz
Used in industrial
tools for cutting,
grinding & sanding.
Diamond is used to
cut all minerals
including diamonds.
Corundum
Diamond
ACTIVITY
Show the approximate value of hardness in the following
minerals:
- Pyrite: It scratches fluorite but it doesn’t scratch
feldspar.
- Silver: It scratches gypsum but it doesn’t scratch
fluorite.
Invent two sentences comparing the hardness of two
minerals. Use the pattern given above.
-
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UNIT 1 – MATERIALS ON THE EARTH
ACTIVITY (Comparatives)
Gypsum is ………………. (soft) than ………………………….
The ……………………….. ( hard ) mineral is…………………….
Topaz is ………………….. (hard ) than quartz.
The ………………. (soft ) mineral is talc.
 Cleavage
When a mineral breaks with smooth flat surfaces.
Cleavage can be described as perfect, good, imperfect,
poor. Galena breaks into cubes and mica breaks into
sheets.
The flat surfaces of these minerals tend to break. Many
minerals do not break smoothly. They have fracture when
they break. Words that describe what a break in a rock or
mineral looks like:
 conchoidal : curved break like what happens with
thick glass or bottle bottom, shell shaped,
can be rough or smooth
 splintery : fibrous
 uneven : rough surface, not smooth
 Specific Gravity (or density) indicates how many times
more the mineral weighs compared to an equal amount of
water.
Some minerals are denser than others. They have a lot
of mass packed into a small volume. High density makes
a mineral very heavy. Gold, silver, and galena are dense
minerals. Gypsum and halite are light minerals.
 Magnetism
Some minerals have special properties. Magnetite is
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UNIT 1 – MATERIALS ON THE EARTH
attracted by a magnet.
 Taste can also serve to identify minerals. Halite tastes
salty.
 Transparency is the ability to transmit light. Minerals
can be transparent, translucent or opaque.
 Fluorescence is the ability to emit visible light when a
mineral is exposed to ultraviolet light.
 Double refraction or Birefringence is the decomposition
of a ray of light into two rays when it passes through a
material. Many minerals are able to decompose light into
two rays but we are able to see it in transparent calcite.
 LABORATORY PRACTICE-2 
PHYSICAL PROPERTIES OF MINERALS
Material:
You will be given different boxes that contain different
elements to solve problems. Before beginning the activity
check the contents of each box. If something is missing,
please tell the teacher.
 Problem 1 (Study of hardness): talc, gypsum,
calcite, quartz, corundum, metal screw, a piece of
glass.
 Problem 2 (Study of magnetism): pyrite, magnetite,
calcite, a magnet.
 Problem3 (Study of cleavage): muscovite (mica),
limonite, gypsum, calcite, galena.
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UNIT 1 – MATERIALS ON THE EARTH
 Problem 4 (Study of fracture): quartz, jasper,
fibrous gypsum, asbestos.
 Problem 5 (Study of colour in monochromatic
minerals): azurite, malachite, sulfur, graphite.
 Problem 6 (Study of colour in alochromatic
minerals): white, yellow, rose, green and smoked
quartz, green and violet fluorite.
 Problem 7 (Study of streak): limonite, hematite,
cinnabar, magnetite, a piece of porcelain.
 Problem 8 (Study of density): barite, quartz,
cylinder, balance.
 Problem 9 (Study of luster): galena, pyrite,
sphalerite, fibrous gypsum, quartz.
 Problem 10 (Study of taste): silvine, halite, talc
and a cellulose paper to dry out.
 Problem 11 (Study of birefringence): transparent
calcite (Iceland spar).
 Problem 12 (Study of mineral habits): gypsum in
rosette habit, gypsum in bladed habit, aragonite
crystals, pyrolusite in dendritic habit, quartz in
geode.
 Problem 13 (Study of fluorescence): fluorite.
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UNIT 1 – MATERIALS ON THE EARTH
HOW DO MINERALS FORM?
Minerals have different origins.
Magma is a mixture of molten rocks deep under the Earth
surface. It is very hot. Some minerals form when magma
cools .The molecules in magma move very fast. The
molecules slow down when magma cools. Then the
molecules form crystals. The magma hardens. It becomes
a solid. Sometimes magma takes a long time to cool. The
crystals have more time to grow and they get very large.
Some minerals form deep in Earth. It is hotter deep in
Earth. Rocks on top press the rocks underneath. The heat
and the pressure produce minerals. When the crust
moves these minerals move to the surface.
Other minerals form when water cools. Magma heats
water deep in the earth. This water has lots of dissolved
minerals. When water cools, minerals become crystals
and they fall to the bottom of the water.
Minerals can also form when water evaporates. Ocean
water contains many dissolved minerals. The ocean water
evaporates and crystals are formed. The salt you use on
food comes from the ocean.
ACTIVITY
Make a picture about four methods minerals are formed.
HOW DO PEOPLE USE MINERALS?

ACTIVITY (internet)
Diamonds, sapphires and rubies are gemstones. People
like them because they are rare and beautiful. They make
jewelry with them. Use the internet to learn more about
gemstones. Write a text in your own words about your
favourite gemstone.
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UNIT 1 – MATERIALS ON THE EARTH
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- Some useful minerals are called ores. An ore is a
mineral that contains a substance people can use. Iron
comes from hematite. People use iron to make nails,
buildings, and ships. Aluminum comes from bauxite.
Aluminum is lightweight. People use it to make foil, cans,
and jets. Iron and aluminum are metals. Metals help
electricity to flow. People can stretch metals into wires.
ACTIVITY  (internet)
Copper and magnesium are also metals. How do people
use them? Which minerals do they come from?
ACTIVITY (at home)
Do a research at home. Make a list of at least 3 minerals
you can find in the kitchen, in the bathroom and in your
bedroom.
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UNIT 1 – MATERIALS ON THE EARTH
HOW ARE ROCKS ALIKE AND DIFFERENT?
A rock is formed by one or more minerals. If you look at
granite, you can see crystals of quartz (white), feldspar
(pink), mica (black), and hornblende (black). Sometimes
the crystals are too small to see.
As we have studied, each mineral has its own properties.
A rock with several minerals has a mixture of properties.
We can identify a rock by its minerals but also by its
colour (light or dark- coloured), density and texture.
Texture refers to the kind of grains: coarse, large, fine,
small, with smooth edge or jagged edge… A rock’s colour,
density and texture depend on how the rock formed.
ACTIVITY
Describe the following rocks according to the colour and
the kind of grains.
1. Basalt
2. Granite
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UNIT 1 – MATERIALS ON THE EARTH
1.
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2.
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 Geologists classify rocks according to their
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UNIT 1 – MATERIALS ON THE EARTH
origin into the following three groups:
Igneous, sedimentary and metamorphic.
WHAT ARE IGNEOUS ROCKS?
All rocks start below Earth´s surface. They are molten, or
melted, deep under the surface. You already know that
molten rock under the surface are called magma. Magma
is less dense than material around, so it rises to the
surface. Sometimes, magma cools before reaching the
surface. It hardens into rock. When magma cools and
hardens an igneous rock form. When magma reaches
the surface without cooling, we call it lava. Lava forms
igneous rocks when it cools and hardens on the surface.
Magma cools slowly below ground. Crystals take a long
time to grow. They become coarse, or large. Lava cools
quickly above the ground. Crystals are smaller.
Sometimes lava cools so quickly that no crystals form.
ACTIVITY
Look again at the granite and the basalt. How are their
crystals? Where do you think they were formed?
Rocks that cooled above ground are called extrusive or
volcanic. They often have cavities in them, produced by
gas. These are called bubbles or vesicles (holes).
Rocks that are cooled below ground are called intrusive.
ACTIVITY (internet)
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UNIT 1 – MATERIALS ON THE EARTH
Obsidian and pumice stone are igneous rocks. Look for a
picture of them, say if they are extrusive or intrusive and
justify your answer.
WHAT ARE SEDIMENTARY ROCKS?
- Sedimentary rocks are made of bits of sediment joined
together. Sediment may be pieces of weathered rock,
shells, or the remains of organisms. Water, wind, and ice
move sediment from a place to another. They deposit
sediment. The sediment drops and makes layers.
Sedimentary rocks form when sediment is compacted and
cemented together. The layers of sediment are heavy.
The top layers squeeze the bottom layers. Bits of
minerals “glue” coarse sediments together. This happen
because water with dissolved minerals squeezes between
coarse pieces of sediment. The water evaporates and
mineral crystals form. The crystals hold the pieces of
sediment together. The sediment becomes a rock.
Weathering, the first step to a “second hand” rock
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UNIT 1 – MATERIALS ON THE EARTH
We often find places like this around mountains:
a)
These piles of broken rock are called scree. The kinds of
changes that break up rocks are called weathering
processes.
In limestone areas we can find caves with a lot of pointed
stalactites and stalagmites. This is caused by rain-water
which is very weak acid. As it falls, it takes carbon dioxide
from the air and becomes very weak carbonic acid.
b)
Physical weathering is caused by expansion effects due to
temperature changes or be due to freezing of water in
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UNIT 1 – MATERIALS ON THE EARTH
cracks. Chemical weathering is caused by reactions
between the minerals in the rock and the environment.
Match a) and b) to physical and chemical weathering
processes.
Second step: The bits of rock must move to a new
home.
The bits of rock will be likely to go down because of
gravity. To make them move they also need energy. The
energy can come from various agents. One of the most
important agents is water. Rivers, for example. But
water isn’t the only way of carrying the bits. The wind is
also an agent. Ice can move rock, too. All these
processes cause erosion-which means actually removing
from its original place. In nature, sediments that travelled
a long way are usually sorted and rounded.
ACTIVITY
Which of the next is made of sediment that travelled a
long way? Which is made of sediment that travelled a
short distance? Explain it.
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UNIT 1 – MATERIALS ON THE EARTH
Sedimentary rocks often hold evidence of how the bits
that make them were transported. Usually, the more
transport, the more energy has affected the bits. They
become rounded and more sorted.
The greater the energy in the process, the bigger the bits
that can move. When the energy gets less, the bigger bits
drop first. Sediment turns to rock slowly by squeezing
under its own weight and by cementing by natural
chemicals. Hard minerals (like quartz) resist rounding
more than soft minerals (like calcite).
ACTIVITY
To make the list of the things that must happen to make
a rock from pebbles of older rocks, let’s fill in the gaps
the next sentences using the verbs given below in the
right order:
First the original rocks must get …………………. Then the
bits must get ……………………to the place where we find
them. They often get …………………….They get ……………………
together. They get …………………… together.
CARRIED (carry); ROUNDED OFF (round); STUCK (stick);
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UNIT 1 – MATERIALS ON THE EARTH
DROPPED (drop); BROKEN UP (break)
Examples of sedimentary rocks:
We classify the rocks according to the sediment size or
the material they are made of.
The sediment can be from small to large: clay, silt, sand
or gravel. The rocks are called:
Clay
Shale______
Silt
Siltstone____
Sand
Sandstone___
Gravel
Conglomerate
Some sedimentary rocks are made of crystals that were
dissolved. When water evaporated, the rock formed. This
is how halite, the rock salt, forms.
Limestone forms when water with calcite evaporates.
Some sedimentary rocks are made of material from
organisms or by organisms.
Coquina is made of shells cemented together and Coral
limestone is made of coral skeletons.
Bituminous coal is a sedimentary rock formed millions of
years ago from dead plants buried in swamps and forests.
People use it for energy.
Sedimentary rocks tell us about Earth’s history. They
often have fossils. Fossils are the remains or imprints of
organisms from the past. Sometimes the remains of dead
organisms were covered with mud, and other sediments.
The sediment, the imprints, and the remains hardened
over time and became rock.
ACTIVITY
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UNIT 1 – MATERIALS ON THE EARTH
Almost all fossils are found in sedimentary rock. Why do
you think fossils cannot be found in igneous rock?
ACTIVITY (internet)
Find out information about the origin of petrol. Write it
down in your own words in four sentences.
WHAT ARE METAMORPHIC ROCKS?
There are high temperatures and a lot of pressure deep
underground. Heat and pressure change rocks. A rock
formed by heat and pressure from another rock is called
metamorphic rock.
This is what happens.
Sometimes a rock deep underground does not melt. It
stays solid.
The mineral grains in the rock may flatten and line up.
The minerals in the rock may change their chemical
composition.
The minerals in the rock may separate into layers of
different densities.
- Each of these things makes a new rock.
Original rock
Granite
Shale
Sandstone
Limestone
Slate
 Metamorphic rock
 Gneiss
 Slate
 Quartzite
 Marble
 Schist
ACTIVITY
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UNIT 1 – MATERIALS ON THE EARTH
Classify the “original rocks” above into the group they
belong to.
Which kind of rocks can transform into metamorphic
rocks?
ACTIVITY
Metamorphic rocks have useful properties. For example,
slate is impermeable and breaks into layers. What is it
used for?
Marble is shinny and colourful. It is easy to carve. What
do people use it for?
THE ROCK CYCLE
Rocks come from other rocks. Rocks change from one
rock to another. Sedimentary rocks are made of broken
pieces of rock. Igneous rocks come from magma or lava.
Metamorphic rocks come from any rock subjected to high
pressure or high temperature. The process of rocks
changing is called rock cycle.
Weathering is part of the rock cycle. Remember that
weathering is breaking rocks into bits and pieces.
ACTIVITY  (internet)
Click on this web and do the exercices.
www.learner.org/interactives/rockcycle/index.htlm
ACTIVITY
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UNIT 1 – MATERIALS ON THE EARTH
Make a diagram about the sequence of events that
happen to rocks into the rock cycle. Use the following
words: weathering, cooling and crystallizing, melting,
compaction and cementation, sediments, deposition,
transportation, consolidation…
Sedimentary rocks
Metamorphic rocks
Sediments
Magma
Igneous rocks
ACTIVITY (internet)
To finish, search the main kind of rocks we can find in
Catalunya. The four basic areas are: granite and
metamorphic areas, calcareous areas, clay areas and
volcanic areas. Identify them and paint the following
map:
 LABORATORY PRACTICE 1
Experiment with malachite
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UNIT 1 – MATERIALS ON THE EARTH
Material:
Some malachite specimens, test tubes, water, limewater,
hydrochloric acid solution, iron nail, rusty nail, fresh nail,
Bunsen, tongs, collection of metals.
Method:
Put some malachite in a clean test-tube.
Add a few drops of water.
- Does the malachite dissolve easily in water?
Put some limewater in another tube.
Add a few drops of dilute hydrochloric acid to the
malachite. Shake the limewater gently.
- What happens to the malachite?
- What happens to the limewater? Explain.
Drop more acid into the malachite until no malachite is
left.
Describe the “malachite tube” until no malachite is left.
Now take a clean iron nail. Drop the nail into the testtube that had the malachite in it and leave it for a few
minutes.
Take out the nail. Describe what has happened to it.
Compare it with a rusty nail and a fresh nail. Put all three
in a Bunsen flame, using tongs. What do you see?
Break all three nails. What do you see?
Compare the nail you left in the “malachite solution” with
a collection of different metals. Which metal has come out
of the malachite?
You have now found TWO materials that can come out of
malachite. What are they?
One is a gas, one a metal. Were they similar in
appearance to the malachite?
Now you should be able to see why we say minerals are
usually COMPOUNDS. They are made of other things
chemically compounded together, and they can be taken
apart again if we use the right chemical methods.
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UNIT 1 – MATERIALS ON THE EARTH
 LABORATORY PRACTICE 2
Physical properties of minerals
Material:
You will be given different boxes that contain different
elements to solve problems. Before beginning the activity
check the contents of each box. If something is missing,
please tell the teacher.
 Problem 1 (Study of hardness): talc, gypsum,
calcite, quartz, corundum, metal screw, a piece of
glass.
 Problem 2 (Study of magnetism): pyrite, magnetite,
calcite, a magnet.
 Problem3 (Study of cleavage): muscovite (mica),
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UNIT 1 – MATERIALS ON THE EARTH
limonite, gypsum, calcite, galena.
 Problem 4 (Study of fracture): quartz, jasper,
fibrous gypsum, asbestos.
 Problem 5 (Study of colour in monochromatic
minerals): azurite, malachite, sulfur, graphite.
 Problem 6 (Study of colour in alochromatic
minerals): white, yellow, rose, green and smoked
quartz, green and violet fluorite.
 Problem 7 (Study of streak): limonite, hematite,
cinnabar, magnetite, a piece of porcelain.
 Problem 8 (Study of density): barite, quartz,
cylinder, balance.
 Problem 9 (Study of luster): galena,
sphalerite, fibrous gypsum, quartz.
pyrite,
 Problem 10 (Study of taste): silvine, halite, talc
and a cellulose paper to dry out.
 Problem 11 (Study of birefringence): transparent
calcite (Iceland spar).
 Problem 12 (Study of mineral habits): gypsum in
rosette habit, gypsum in bladed habit, aragonite
crystals, pyrolusite in dendritic habit, quartz in
geode.
 Problem 13 (Study of fluorescence): fluorite.
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UNIT 1 – MATERIALS ON THE EARTH
PHYSICAL PROPERTIES OF MINERALS
Method:
- Take a box and check the material inside.
- Read the information about your box and the
problem that’s to be solved.
- Follow the instructions and solve the problem.
- Write down the information and solutions.
Draw a picture or take a photograph of each
mineral in the box.
*Problem 1 (Study of hardness): Hardness is how
difficult is to scratch a mineral. This property
depends on the union of the atoms involved.
a) Check which mineral scratches most easily .
Make a list from the softest to the hardest.
b) Now scratch every mineral with the metal
screw. Which place on the list would you put the
screw?
c) Take each mineral and try to scratch the glass.
Which minerals can scratch the glass?
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UNIT 1 – MATERIALS ON THE EARTH
To sum up: Which mineral is the softest? And
which is the hardest? Why?
*Problem 2(Study of magnetism): A mineral is
magnetic if it is attracted by a magnet.
Find out if the minerals in the box are magnetic or
not. Write down your answers.
*Problem 3 (Study of cleavage): Cleavage is the
way a mineral breaks. Many minerals break along
flat planes, or cleavages—some in only one
direction, other in two directions, and some in three
directions or more.
In this case the minerals have already been broken.
Observe them and write down the name of those
that have got cleavages.
*Problem 4 (Study of fracture): When a mineral
breaks in irregular surfaces we speak about
fracture. If the mineral breaks with smooth flat
surfaces we speak about cleavage. There are
different words to describe what a break in a rock
or mineral looks like:
-conchoidal : curved break like what happens with
thick glass or bottle bottom, shell shaped,
can be rough or smooth
-splintery : fibrous
-uneven : rough surface, not smooth
In this case the minerals have already been broken.
Observe them carefully and write down which of
them has fracture. Write down which kind of
fracture they have.
*Problem 5 (Study of colour in monochromatic
minerals):
There are minerals that always have the same
colour. They are called monochromatic.
All the minerals that you have in the box are
monochromatic. Write down the colour of each
specimen.
*Problem 6 (Study of colour in alochromatic
minerals): There are minerals that can have very
different colours, a variety of colours.
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UNIT 1 – MATERIALS ON THE EARTH
All the minerals you have in the box are
alochromatic. Write down the colours of all the
specimens. Which mineral of the box shows a major
variety of colours?
*Problem 7 (Study of streak): If you rub a mineral
against a streak plate you will get a powder.The
colour of this powder is the authentical colour of the
mineral.
Rub each mineral on the porcellain plate. Write
down the colour you observe. Is this colour
different from the colour of the mineral?
*Problem 8 (Study of density): Remember that
density is the relationship between mass and
volume: weight/volume.
To calculate density you have to fill a cylinder with
water to a certain volume. You write down the
volume of water (V). Then, you add the specimen
inside the cylinder and you write the new volume
(V´). The difference between both (V-V´) is the
volume of the mineral. Weigh the mineral and write
down its mass.
Can you calculate the density of the mineral? What
is the value?
*Problem 9 (Study of luster): Luster is the way a
mineral reflects light. We can describe it as metallic
(very shinny) or non-metallic. There are different
words to describe non-metallic luster: dull/earthy,
waxy (like the surface of a candle), greasy /oil,
pearly, silky (like a piece of cloth), glassy/vitreous
(looks like a glass), resinous, adamantine (like a
diamond).
Write down which kind of luster each specimen has.
*Problem 10 (Study of taste): Some minerals have
a characteristic taste and this property is useful in
identifying them.
Water the top of three fingers and touch each
specimen with a different finger. Taste with the tip
of your tongue every finger. Describe the flavour of
each mineral.
*Problem 11 (Study of birefringence): This property
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UNIT 1 – MATERIALS ON THE EARTH
is very common in most of the minerals.
Tick a dot (*) on your sheet. Place the transparent
calcite sample over the dot and look at it. What can
you observe? Explain what you think has happened.
*Problem 12 (Study of mineral habits):
In some minerals there are typical associations of
crystals.
Match the following crystal habits to the
correspondent mineral specimen:
a) bladed habit, b) rosette habit, c) dendritic habit,
d) hexagonal habit e) geode
*Problem 13 (Study of fluorescence):
We can check this property with an ultraviolet
lamp. Take a fluorite sample and place it under the
uv lamp. Explain what happens.
LABORATORY PRACTICE 3
Is COLOUR a good way TO IDENTIFY MINERALS?
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UNIT 1 – MATERIALS ON THE EARTH
Some specimens of quartz, calcite, halite and feldspar are
normally white. We need some other ways of telling them
apart.
Using the property of hardness, try to distinguish calcite
from quartz: Rub an edge of the quartz on a surface of
calcite .Rub an edge of the calcite on the quartz. What do
you see?
Another test you can do: Calcite is a carbonate.
Carbonates produce carbon dioxide (gas) when a drop of
hydrochloric acid is put onto the specimens. After putting
one small drop of acid, rinse off the acid.
Another test is taste. Just touch the mineral with the tip
of your tongue.
You can try these tests on all the four minerals and write
down what you find in the following table:
Quartz
Calcite
Halite
Feldspar
Colour?
Shiny/dull?
Is it the
hardest?
Is it the
softest?
Has it a taste?
What does
acid do?
PART 2 ( rocks: granite, sandstone, some types of limestone)
One mineral of these minerals makes up a small part of
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UNIT 1 – MATERIALS ON THE EARTH
the granite. Most of the sandstone is this mineral. Is this
quartz, calcite or halite? Try your tests to INFER which
one.
Granite also contains two kinds of feldspar. Feldspar is
actually the most common mineral in the world. One
variety is white, what colour is the other?
Investigate some types of limestone. Which of the four
minerals is in limestone?
 LABORATORY PRACTICE 4
Let’s make a geode of blue Copper Sulfate Crystals
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UNIT 1 – MATERIALS ON THE EARTH
Geodes are a type of rock containing crystals. Normally,
millions of years are required for flowing water and
minerals to deposit crystals. You can make your own
'geode' in only a few days. Grow beautiful translucent
blue crystals of copper sulfate pentahydrate inside an egg
shell to make your own geode.
Material:
-
an egg
-
hot water
-
copper sulfate
Method :
1.
First, you need to prepare the eggshell. A natural
geode forms inside a mineral. For this project, the
mineral is the calcium carbonate of an eggshell.
Carefully crack open an egg, discard the egg, and
keep the shell. Clean the egg from the shell. Try for a
clean break, to create two halves of the shell, or you
may wish to just remove the top of the shell, for a
more ball-shaped geode.
2.
In a separate container, add copper sulfate to 1/4
cup of hot water. The amount of copper sulfate isn't
exact. You want to stir copper sulfate into the water
until no more will dissolve. More is not better! It
should take a few pinches of solid material to make a
saturated solution.
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UNIT 1 – MATERIALS ON THE EARTH
3.
Pour the copper sulfate solution into the eggshell.
4.
Place the eggshell in a location where it can remain
undisturbed for 2-3 days. You may want to place the
eggshell in another container to keep it from falling
over.
5.
Observe your geode each day. Crystals should
appear by the end of the first day and will be at their
best after the second or third day.
6.
You can pour out the solution and allow your geode
to dry after a couple of days or you can let the
solution fully evaporate (week or two).
Tips:
1.
Even a small increase in the temperature of the
water will greatly affect the amount of copper sulfate
(CuS04 . 5H20) that will dissolve.
2.
Copper sulfate is harmful if swallowed and can
irritate skin and mucous membranes. In case of
contact, rinse skin with water.
3.
Copper sulfate pentahydrate crystals contain water,
so if you want to store your finished geode, keep it in
a sealed container. Otherwise water will evaporate
from the crystals, leaving them dull and powdery. The
gray or greenish powder is the anhydrous form of
copper sulfate.
4.
The archaic name for copper (II) sulfate is blue
vitriol.
5.
Copper sulfate is used in copper plating, blood tests
for anemia, in algicides and fungicides, in textile
manufacturing, and as a dessicant.
LABORATORY PRACTICE 5
Describing rocks
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UNIT 1 – MATERIALS ON THE EARTH
We have heard of lots of kinds of rocks. Granite,
sandstone, limestone and so on. How do we know which
one is which?
Part 1
You will be given a set of different types of “earth
materials”. Try to put them into groups of similar types.
Write down why you put them together, and compare
your groups with those made by other groups.
Do you agree?
Part 2
We need to find out how to describe what we see. The
best way is to compare two types of rock.
Take two good-sized specimens of granite and sandstone.
Observe them carefully. How many differences can you
find? The chart will help you.
GRANITE
-
Colour?
-
Size of bits?
-
Shiny or dull?
-
How many different types of bits?
-
Anything else?
SANDSTONE____
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UNIT 1 – MATERIALS ON THE EARTH
 LABORATORY PRACTICE 7
Identification of rocks
You are going to work as geologist teams. You will have
to identify the rocks after observing them carefully. You
will have to say if they are sedimentary, igneous or
metamorphic and justify your decision. At the end of the
class, each team will show the results to the rest of the
class and we will discuss the answers.
Each team will be given a collection of 6 rocks and an
observation card. You will study each sample during 5
minutes. The observation card will help you to support
your decision.
Rock 1
It can be scratched with fingernail
It is lighter than the other rocks
It has got a bright colour
We found it at the top of a mountain
It makes your clothes dirty
It contains fossils
Rock 2
It is multi-coloured
It is heavier than the other rocks
It is very hard
It contains crystals
It is difficult to break
It reflects light
Rock 3
It is fragile, so it breaks easily
It has got layers
It is almost black
It is quite resistant
It can be used in roofs
It is odourless
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UNIT 1 – MATERIALS ON THE EARTH
Rock 4
It is not especially heavy
It cannot be scratched with fingernail
It is dark
We found it buried in a watercourse
It has not got crystals
Rock 5
The rock contain bits of other rocks
It can break
It makes your clothes dirty
It is easy to scratch
We found it on the base of a mountain
Rock 6
It is bright coloured
It is very hard
It is difficult to scratch
It reflects the light
We found it in a high altitude
We can use it as we find it in nature
OBSERVATION CARD:
Rock 1
We think this rock is ………. because ……….
Rock 2
Rock 3
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UNIT 1 – MATERIALS ON THE EARTH
Rock 4
Rock 5
Rock 6
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UNIT 1 – MATERIALS ON THE EARTH
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