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Belén López
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MINERALS
A mineral is a natural, inorganic and solid substance that has a defined chemical
composition and an ordered structure. Minerals can be made of one or more chemical
elements.
Every mineral can be described by various physical characteristics.
Density: is the mass of the mineral divided by its volume. The denser a mineral is the
more compacted their atoms are.
Hardness: it defines how much a mineral can resist scratching. The most common way
to measure hardness is to use Mohs scale. It is defined by numbers, so a mineral with a higher
number scratches those below it. We can also scratch some minerals, like talc and gypsum
with our fingernail; using a knife we can also scratch calcite and fluorite. A glass can scratch
those four, apatite and feldspar, but glass is scratched by quartz, topaz, corundum and
diamond. This scale says that diamond is the hardest mineral while talc is the softer.
Cleavage: is related to the way a mineral is broken in plane surfaces. When you hit a
mineral, it can be broken in sheets, cubes or any geometrical figure. But if a mineral is broken
in an anarchic way, we call it fracture.
Luster: it indicates how a mineral reflects light. To describe the luster we use
adjectives.
Streak: it refers to the color of a mineral in powdered form, which may or may not be
identical to its body color.
1. To describe luster we use adjectives. In English, a way to form adjectives is to add –y
at the end of a noun, for example, if a thing is difficult to solve, we can say that it’s
difficulty. Make sentences to describe the luster of these minerals using adjectives.
Diamond looks like a glass. (Glass  glassy) Diamond has a glassy luster.
Pyrite shines like a metal (Shine______) Pyrite is _______.
Talc looks like a pearl. (______  _______) Talc has a ___________________.
Jade luster resembles a candle. (Wax  _____) Jade has a ___________________.
2. Other way to form adjectives is to add –ish to a color. We can say that a mineral has
a red streak or that its streak is reddish. Complete the description according to each
mineral streak color.
A hematite is black, but it has a red streak. Its streak is ______.
Chalcopyrite’s streak is green____.
Bornite is a black pearly mineral. Its streak is _______.
Sphalerite is yellow. _______________________________.
3. Look at the Mohs scale and make sentences comparing the hardness of minerals.
(Remember to use the structure Mineral + hard/soft + –er + than + mineral). What
do letters A, B, C, D refer to? Make sentences using mineral + can/can`t be scratched
by + A/B/C/D.
4. Look at the chemical formula of the minerals in Mohs scale. Make sentences saying
what are they made of. Use the structure mineral + is made of + (elements).
Belén López
belenciencias.blogspot.com.es
MOHS SCALE
Belén López
belenciencias.blogspot.com.es
ROCKS
Rocks are made of one or more minerals. There are three main types of rocks,
sedimentary, magmatic or igneous, and metamorphic rocks.
Sedimentary rocks are formed by sedimentation of particles. When weathering erodes
a rock, we obtain sediments that are transported and deposited into a sedimentary basin.
After a while these sediments suffer a process of compacting and cementation that transform
the sediments into rocks. Two examples of sedimentary rocks are sandstone and limestone.
Magmatic or igneous rocks are formed through the cooling and solidification of
magma or lava. There are two types of igneous rocks, plutonic and volcanic rocks. If magma
cools and solidifies slowly within the Earth’s crust, a plutonic rock is formed, like granite. When
magma reaches the surface we call it lava, and when lava cools and solidifies we obtain a
volcanic rock, like pumice.
Metamorphic rocks are formed by the application of high pressure or temperature.
These two factors change the structure of the rocks, so they are transformed to a different
rock. If metamorphism occurs to clay we can obtain slate.
THE ROCK CYCLE
Every rock can be transformed into another depending on the processes that occur.
To obtain a sedimentary rock, erosion compacting and cementation must occur. By
these processes an igneous, metamorphic or sedimentary rock, can be transformed into a
sedimentary rock.
If any rock is melted it is transformed into magma, and when it solidifies, we obtain an
igneous rock.
The same happens with a metamorphic rock, if we apply high pressure and high
temperature to a rock it suffers a metamorphic process and we obtain a metamorphic rock.
INTERACTIVE ROCK CYCLE  http://www.learner.org/interactives/rockcycle/diagram.html
Belén López
belenciencias.blogspot.com.es
5. Complete the table about the different types of rocks. Look for two more examples
of each rock.
TYPE OF ROCK
PROCESSES
EXAMPLES
6. Color the arrows and include the color key in the rock cycle.