Download Rocks - liceo Joyce

Progetto CLIL
Liceo statale «James Joyce» di Ariccia
A.S. 2015/2016
Geology: MINERALS AND ROCKS
Lesson 2 – Minerals and rocks
Dott.ssa Giulia Botticelli
Dott. Mario Silvestri
Why should we study rocks?
Geologists study rocks because they contain clues about what the Earth
was like in the past. We can assemble a historical record of a planet and
trace events that occurred long before humans roamed our planet.
What is a mineral?
Elements:
Elements are atoms, the smallest piece that we can split matter into
(except for subatomic particles and other things that we'll leave to the
physicists). Different elements have different properties. Take two
different elements: iron and helium. Iron is very different than helium.
You wouldn't fill a balloon with iron any more than you would try to build
a bridge out of helium.
Minerals:
Elements often are stacked together with other elements to form
minerals. Minerals are simply a collection of one or more elements that
are stacked neatly together in a form called a crystal structure.
What is a rock?
Rocks:
Rocks are a composed of one or more minerals. A rock can be made up
of only one mineral or, as shown in the figure, a rock can be made up of
a number of different minerals.
So, rocks are composed of one or more minerals and minerals are
composed of one or more elements.
.
What is a mineral?
Elements:
Elements are atoms, the smallest piece that we can split matter into
(except for subatomic particles and other things that we'll leave to the
physicists). Different elements have different properties. Take two
different elements: iron and helium. Iron is very different than helium.
You wouldn't fill a balloon with iron any more than you would try to build
a bridge out of helium.
Minerals:
Elements often are stacked together with other elements to form
minerals. Minerals are simply a collection of one or more elements that
are stacked neatly together in a form called a crystal structure.
Periodic table of the elements
What is a mineral?
Elements:
Elements are atoms, the smallest piece that we can split matter into
(except for subatomic particles and other things that we'll leave to the
physicists). Different elements have different properties. Take two
different elements: iron and helium. Iron is very different than helium.
You wouldn't fill a balloon with iron any more than you would try to build
a bridge out of helium.
Minerals:
Elements often are stacked together with other elements to form
minerals. Minerals are simply a collection of one or more elements that
are stacked neatly together in a form called a crystal structure.
Mineral classes
Some common mineral classes include:
Silicates
Silicates have a silicon atom surrounded by four oxygen atoms. Quartz (silicon dioxide, SiO2)
is a common silicate.
Carbonates
Carbonates have a carbon atom surrounded by three oxygen atoms. Calcite (calcium
carbonate, CaCO3) is a common carbonate found in limestones.
Sulfates
Sulfates have a sulfur atom surrounded by four oxygen atoms. Gypsum (calcium sulfate,
CaSO4 2H2O) is a common sulfate.
Oxides
Oxides contain oxygen often combined with only one other (usually metal) element.
Hematite (iron oxide, Fe3O4) is an example of an oxide.
Halides
Halides are salts (sodium chloride, NaCl, or table salt being one particular kind of salt).
All minerals within a mineral class are similar, but they also have important differences. For example, calcite (calcium
carbonate), rhodochrosite (manganese carbonate), and siderite (iron carbonate) are all different kinds of carbonates.
They all have the same carbon atom surrounded by three oxygen atoms, but they also have different atoms, such as
manganese, iron, or calcium.
Mineral classes
Silicates
- Quartz
Often light colored and found in all types of rocks.
- Feldspar
Also very common and found in many different kinds of rocks. (Image is of
microcline, a specific type of feldspar.)
- Mica
Flaky mineral often present as black flecks in granite. (Image is of biotite, a specific
type of mica.)
- Amphibole
A dark colored mineral found in a variety of igneous andmetamorphic rocks. (Image
is of hornblende, a specific type of amphibole.)
- Pyroxene
A dark colored mineral often found in igneous rocks such as basalt. (Image is of
diopside, a specific type of pyroxene.)
- Clays
These are also called phyllosilicates and are formed when a rock is weathered.
(Image is of talc, a specific type of clay-forming mineral.)
Mineral classes
Carbonates
- Calcite
Limestones (sedimentary rocks) are formed from calcite.
Sulfates
- Gypsum
Gypsum is often found in desert playas and dry lakes
Oxides
- Hematite
Hematite is also known as rust and its reddish color can be
seen in many rocks
Rocks
Just like minerals, there are many different kinds
of rocks. Geologists group rocks into three
different categories; igneous, sedimentary, and
metamorphic.
• Igneous rocks form from magma or lava
• Sedimentary rocks form from pieces of other
rocks or are formed by minerals being precipitated
from water
• Metamorphic rocks form by recrystallizing the
minerals in a rock under high pressures or
temperatures
Rocks
Rocks are combinations of one or more minerals that we find in nature.
For example:
Limestone is composed of only one mineral – calcite
Basalt is commonly composed of three minerals – feldspar, pyroxene, and olivine
Granite is commonly composed of five minerals – two kinds of feldspar, mica,
amphibole, and quartz
Limestone
Basalt
Granite
Remember the rock cycle!
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks
Rocks
Take a look at the rocks...
If you have any questions...
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