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3
The Geosphere
37.
The following graph shows how seismic waves move
around the planet. Which seismic wave is traveling at
a higher speed? Which layers of the Earth do they go
through?
Speed of siesmic wave (km/s)
Depth (km)
0
Moho
Gutenberg Lehmann
Waves S
Mantle
Outer
core
Inner
core
Waves P
0
3
6
9
12
1000 2000 3000 4000 5000 6000
P waves are traveling at a higher speed.
P waves go through all layers of the Earth’s interior, while S
waves only go through the crust and the mantle.
Minerals
38.
Which property of materials does
the image show?
Tenacity and resistance, that shows
when a mineral breaks.
39.
Describe four properties ofminerals.
Open answer. Students could choose four of the several
properties of minerals mentioned in the unit.
40.
Explain if an ice cube and coral used in jewelry are
minerals or not.
An ice cube is not a mineral because it is made up by a
human being when freezing water and giving it an artificial
geometrical shape. On the other hand, the natural ice is
considered a mineral.
The coral used in jewelry is not a mineral because it is not
inorganic, it is formed by an animal called coral.
41.
Investigate and then copy and complete the table in
your notebook.
Ore
Metal
Bauxite
Aluminium
Blend
Zinc
Chalcopyrite
Copper
Cassiterite
Tin
Cinnabar
Mercury
Galenite
Lead
Hematite
Iron
42.
According to the Mohs scale, what is the hardness of
a mineral that scratches orthoclase but is scratched by
quartz?
The hardness will be between 6 to 7 according to the Mohs
scale.
43.
Explain how you can distinguish white quartz from
orthoclase which is the same colour.
We can distinguish them by other characteristics or properties,
like the streak or the lustre. The streak in the quartz is always
white. In case there are a fragment of quartz and another one
of orthoclase, you can compare their hardness as the quartz
scratch the orthoclase, but not the other way round.
44.
Find out why the color and streak of a mineral isn’t
always the same.
Because the colour of the streak or the powder produced
when a mineral is scratched is actually its ‘original colour’,
according to its chemical composition and its crystalline
structure. The colour of a mineral could have been influenced
by external factors and caused a variation on its original
colour.
45.
Find out why pyrite is also referred to as ‘fool’s gold’.
Because its appearance (colour and lustre) is similar to the
gold, but its commercial value is much cheaper. Historically,
millions of people were fooled by buying pyrite rather than
gold.
Rocks
46.
Explain the three characteristics that are used to classify
rocks.
The three characteristics that are used to classify rocks are:
- Composition: minerals that make up the rock.
- Texture: size and arrangement of the minerals in the rock.
- Origin: the way that the rock was formed.
47.
Pumice is a rock that floats in water. Why do you think
this is? Is it a natural or an artificial rock? Justify your
answer.
Because it has many small holes in the surface. These were
formed by gases that were in the rock before solidified.
48.
Copy the following terms in two columns in your
notebook and then match them:
Limestone
Detritial Sedimentary
Granite
Non-detritial Sedimentary
Clay
Plutonic
Marble
Volcanic
Basalt
Foliated metamorphic
Chalk
Non-foliated metamorphic
49.
Are there any rocks which are not composed of
minerals? What type of rocks are they?
Yes, coal and petroleum. These rocks are classified by looking
at the origin of the sediments that compose them and are
called sedimentary rocks.
50.
When 1 kg of granite was analysed in the laboratory
using different chemical processes they obtained 250
g of a white mineral, 300 g of another mineral, almost
black, and the rest was a grey mineral.
CONSOLIDATION
