Transcript What is a mineral?

CHAPTER 2 – SECTION 1
MINERALS
Open your books to page 30
Please take notes over the yellow slides!
MINERALS

We use products made from minerals everyday
such as ceramics, metals, and even some paper
items are made from minerals. As a matter of
fact, the pencil you write with each day is made
from the mineral graphite.
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See figure 1 on page 30. Can you identify what
objects are made of minerals?
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Minerals are the building blocks of all rocks.
There are about 4,000 minerals that have been
identified.
WHAT IS A MINERAL?
 Minerals
- A naturally occurring, inorganic
solid with a definite chemical composition
and an orderly arrangement of atoms
WHAT DOES THAT MEAN???
There are four characteristics of minerals:

Naturally occurring – made by nature (no help
from humans).

Inorganic –they aren’t made by life processes
WHAT DOES THAT MEAN???
Definite chemical composition – made of one or
more elements (see periodic table of elements in
back of book).
 There are actually eight elements that make up
most minerals. They are oxygen, silicon,
aluminum, iron, calcium, sodium, potassium, and
magnesium. These elements make up about 98%
of Earth’s crust.
 SO…elements are the building blocks of minerals
and minerals are the building blocks of rocks.
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WHAT DOES THAT MEAN???
Orderly arrangement of atoms – this means they
have a solid, crystalline structure.
 Crystalline means that the atoms are arranged in
a pattern that is repeated over and over again. For
example, graphite atoms are arranged in layers,
but an opal (gemstone) is not a mineral because
the pattern does not repeat.
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Gases (and water) are not minerals. Minerals must
have a definite shape. Only solids can be minerals.
FILL IN THE BLANKS ON YOUR NOTES…
Minerals are the building
blocks of all rocks.
What is a mineral?
Naturally occurring - made by nature
Inorganic - they aren’t made by life process
Definite chemical composition – made of one of
more elements.
Orderly arrangement of atoms - this means they have a solid,
crystalline structure.
STRUCTURE OF MINERALS
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Crystal – a solid where the atoms are arranged in
an orderly, repeated pattern.
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Remember – minerals have a crystalline structure.
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You can see evidence of atoms arranged in an
orderly pattern when you look at certain types of
crystals. (Exp: geode)
STRUCTURE OF MINERALS
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Rose Quartz does not look orderly on the outside,
but the crystal structure on the inside is orderly
and arranged as a crystal structure.
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The crystal shape is not as definite because the
rose quartz developed in a tight space and the
geode developed in an open space.
STRUCTURE OF MINERALS
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There are six major crystal systems. Minerals are
often classified by their crystal structure. (See pg.
32 for a list of structures)
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Crystals can form by many different processes.
We will learn about two of those
processes…crystals that form from magma and
crystals that form from solutions of salts.
SIX CRYSTAL STRUCTURES PG. 32
Cubic
Hexagonal
Tetragonal
Triclinic
Orthorhombic
Monoclinic
FILL IN THE BLANKS ON YOUR NOTES…
Structure of Minerals
Crystal Structure – a solid where atoms are
arranged in an orderly, repeated pattern
There are
6
major crystal systems
CRYSTALS THAT FORM FROM MAGMA
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Magma is hot melted rock below the Earth’s
surface.
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This magma cools as it reaches Earth’s surface, or
even if it’s trapped below the surface.
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As the magma cools, the atoms lose heat energy,
move closer together, and begin to combine into
compounds.
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During this process, atoms from the different
compounds begin to arrange themselves into
orderly, repeating patterns.
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The type and amount of elements present in the
magma partly determine which minerals will form.
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Also, the size of the crystals that form depends partly on how
rapidly the magma cools.
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When magma cools slowly, the crystals are large. This is because
the atoms have time to move together and form larger crystals
before the cooling process ends.
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When magma cools quickly, the crystals are small. There is not
enough time from large crystals to form so they remain small.
CRYSTALS THAT FORM FROM A SOLUTION
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Crystals can form from solutions as water
evaporates or if too much of a substance is
dissolved in water. (See picture of salt deposits
on pg. 33. figure 4).
FILL IN THE BLANKS ON YOUR NOTES…
Crystals Form in Many Different Processes
Crystals can form from hot magma.
•
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When magma cools slowly , the crystals are large.
When magma cools quickly , the crystals are small
Crystals can form from a solution.
•
Happens when water evaporates or if too much of a
substance is dissolved in water.
MINERAL COMPOSITIONS AND GROUPS
90 elements occur naturally in Earth’s crust.
 Approx. 98% of the Earth’s crust is made up of 8
out of the 90 known elements.
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These 8 elements are oxygen, silicon, aluminum, iron, calcium, sodium,
potassium, magnesium
Of the thousands of known minerals, only a few
dozen are common and are composed mainly of
the eight most common elements found in Earth’s
crust.
Silicates – the most common rock forming mineral
group
 They contain silicon and oxygen, and usually one
or more other elements.
 Silicon and oxygen are the two most abundant
elements found in Earth’s crust.
 These two elements alone combine to form the
basic building blocks of most minerals in the
Earth’s crust.
 Most minerals are composed from silicone and
oxygen and combined with other elements
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FILL IN THE BLANKS ON YOUR NOTES…
Minerals Compositions and Groups
90 elements occur naturally in Earth’s crust
98% of Earth’s Crust is made up of 8 out of 90
elements.
Silicates – the most common rock forming mineral group.
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They contain both silicon and oxygen .
Most minerals are composed from silicone and oxygen.
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