Post on 26-Jun-2020
MINERALSCHAPTER 4 SECTION 1
What are minerals?, video
https://www.youtube.com/watch?v=tnwRqlpWo7Y
MINERALS
Vocabulary
• Mineral
• Silicate
• Silicon-oxygen tetrahedron
• Carbonates
• Oxides
• Sulfates and sulfides
• Halides
• Native elements
• Streak
• Luster
• Crystal forms
• Hardness
• Mohs scale
• Cleavage
• Fracture
• density
WHAT ARE THE FIVE CHARACTERISTICS OF A MINERAL?
Video: https://www.youtube.com/watch?v=8a7p1NFn64s
1. A mineral is a naturally occurring, inorganic solid with an
orderly crystalline structure and a definite chemical
composition.
a)Examples of minerals in everyday life:
• Salt
• Lead in pencils contains graphite
• Make-up or powders have mineral talc
• dentist’s drill has minerals so it can drill through tooth enamel
• Quartz is the main ingredient used in windows and drinking
glasses
WHAT ARE THE FIVE CHARACTERISTICS OF A MINERAL?
WHAT ARE THE FIVE CHARACTERISTICS OF A MINERAL?
For an Earth material to be considered a mineral, it
must have the following characteristics:
1.Naturally occurring, formed by natural geological
processes
2.Solid substance, Minerals are solids within the
temperature ranges that are normal for Earth’s surface.
WHAT ARE THE FIVE CHARACTERISTICS OF A MINERAL?
3.Orderly crystalline structure, the atoms or ions are
arranged in an orderly and repetitive manner.
WHAT ARE THE FIVE CHARACTERISTICS OF A MINERAL?
4. Definite chemical composition, chemical compounds made up of
two or more elements.
a) Gold and silver are exceptions
b) Mineral quartz is 2 oxygen atoms for every one silicon atom (SiO2)
5. Generally considered inorganic, Most minerals are inorganic
crystalline solids found in nature.
a) Salt (halite) is inorganic
b) Sugar is a crystalline structure but is organic
WHAT PROCESSES RESULT IN THE FORMATION OF MINERALS?
There are four major processes by which minerals form:
crystallization from magma, precipitation, changes in pressure and
temperatures, and formation from hydrothermal solutions.
1. Crystallization from Magma, Magma is molten rock. It forms deep
within Earth. As magma cools, elements combine to form
minerals such as feldspar, quartz, muscovite, and hornblende.
The first minerals to crystallize from magma are usually those
rich in iron, calcium, and magnesium.
WHAT PROCESSES RESULT IN THE FORMATION OF MINERALS?
WHAT PROCESSES RESULT IN THE FORMATION OF MINERALS?
2. Precipitation. The water in Earth’s lakes, rivers, ponds, oceans,
and beneath it surface contains many dissolved substances. If
this water evaporates, some of the dissolved substances can
react to form minerals. Changes in in water temperature may also
cause dissolved material to precipitate out of a body of water.
Two common minerals that form in this way are limestone caves
and halite and calcite.
WHAT PROCESSES RESULT IN THE FORMATION OF MINERALS?
WHAT PROCESSES RESULT IN THE FORMATION OF MINERALS?
3. Pressure and Temperature. Some minerals, including talc and
muscovite, form when existing minerals are subjected to changes
in pressure and temperature. An increase in pressure can cause
a mineral to recrystallize while still solid. The atoms simply
rearranged to form more compact minerals. Changes in
temperature can also cause certain minerals to be come
unstable. Under these conditions, new minerals form, which are
stable at the new temperature
WHAT PROCESSES RESULT IN THE FORMATION OF MINERALS?
4. Hydrothermal Solutions. A hydrothermal solution is a very hot
mixture of water and dissolved substances. Hydrothermal
solutions have temperatures between about 1000C and 3000C.
When these solutions come into contact with existing minerals,
chemical reactions take place to form new minerals. Also, when
such solutions cool, some of the elements in them combine to
form minerals such as quartz and pyrite.
HOW CAN MINERALS BE CLASSIFIED?
1. Silicates, the most common groups of minerals on Earth. Silicon and
oxygen combine to form a structure called silicon-oxygen tetrahedron.
a) Tetrahedron, consists of one silicon atom and four oxygen atoms,
providing the framework of every silicate mineral. Except for a few
silicate minerals, such as pure quartz (SiO2), most silicates also contain
one or more other elements.
HOW CAN MINERALS BE CLASSIFIED?
b) Silicon-oxygen bonds are very strong.
c) Some minerals, such as olivine, are made of millions of single tetrahedra.
d) In minerals such as augite, the tetrahedra join to form single chains.
e) Hornblende has double chains of tetrahedra
f) Micas has tetrahedra that join to form sheets.
The internal
structure of a
mineral affects it
properties
HOW CAN MINERALS BE CLASSIFIED?
g) Silicate minerals can often provide scientists with clues about the
conditions in which minerals are formed by:
i. Most silicate minerals crystalize from magma as it cools; this can happen
near the Earth’s surface or at great depths. The place of formation and
chemical composition of the magma determine which silicate minerals will
form.
ii. Silicate minerals formed at Earth’s surface when existing minerals are
exposed to weathering. Clay minerals, which are silicates, form this way.
iii. Other silicate minerals form under the extreme pressures that occur with
mountain building.
HOW CAN MINERALS BE CLASSIFIED?
2. Carbonates, are minerals that contain the elements
carbon, oxygen, and one or more other metallic
elements.
a) Calcite (CaCO3), most common carbonate mineral
b) Dolomite, limestone, marble
HOW CAN MINERALS BE CLASSIFIED?
3. Oxides, are minerals that contain oxygen and one or
more other elements, which are usually metals.
a) Rutile (TiO2), forms as magma cools beneath Earth’s
surface; titanium oxide
b) Corundum, (Al2O3), form when changes in temperature
and pressure occur.; aluminum oxide
c) Hematite, (Fe2O3), forms when existing minerals are
exposed to liquid water or moisture in the air; iron oxide
HOW CAN MINERALS BE CLASSIFIED?
4. Sulfates and sulfides, are minerals that contain the
element sulfur.
a) Anhydrite (CaSO4) and gypsum (CaSO4 + 2H2O) form
when mineral-rich waters evaporate
b) Galena (PbS), sphalerite (ZnS), and pyrite (FeS2) often
form from thermal, or hot-water solutions
HOW CAN MINERALS BE CLASSIFIED?
5.Halides, are minerals that contain a halogen ion plus one
or more other elements.
a) Halogens are elements from Group 7A of the periodic
table. This group includes the elements fluorine (F) and
chlorine (Cl).
b) Halite (NaCl), table salt
c) Fluorite (CaF2) is used in making steel; forms when salt
water evaporates
HOW CAN MINERALS BE CLASSIFIED?
6.Native elements, are minerals that only contain one
element or type of atom.
a)Gold (Au), silver (Ag), Copper (Cu), sulfur (S)
b)carbon (C); diamonds, graphite (pencils)
c)Some native elements form from hydrothermal
solutions.
PROPERTIES OF MINERALS
VOCABULARY
Streak
Luster
Crystal form
Hardness
Mohs scale
Cleavage
density
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
Video: https://www.youtube.com/watch?v=32NG9aeZ7_c
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
1.Color
a)Small amounts of different elements can give the
same mineral different colors.
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
2.Streak
a)Streak is the color of a mineral in its powdered form.
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
3.Luster
a)Luster is used to describe how light is reflected from
the surface of a mineral.
b)Minerals that have the appearance of metal are said to
have a metallic luster
c)Nonmetal luster are described as vitreous or glassy,
pearly, silky, earthy, adamantine or brilliant (like a
diamond)
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
4. Crystal form
a.Crystal form is the visible expression of a mineral’s internal
arrangement of atoms.
b.Every mineral has a crystal from based on one of six distinct
crystal systems (slide 36)
c.When a mineral forms slowly and without space restrictions, it
will develop into a crystal with well form faces – sides, top and
bottom.
d.Crowding results in an intergrown mass of small crystals. None
of these crystals shows its crystal form.
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
5. Hardness
a)Hardness is the measure of the resistance of a mineral to being
scratched.
b)You can find this property by rubbing the mineral against
another mineral of known hardness. One will scratch the other,
unless they have the same hardness.
c)Mohs scale consists of 10 minerals arranged from 10 (hardest)
to 1 (softest)
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
6. Cleavage
a)Cleavage is the tendency of a mineral to cleave, or break, along
flat, even surfaces.
b)In the atomic structure of a mineral, some bonds are weaker
than others. These weak bonds are places where a mineral will
break when it is stressed.
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
7. Fracture
a)Minerals that do not show cleavage when broken are said to
fracture.
b)Fracture is the uneven breakage of a mineral.
c)Quartz breaks into conchoidal fracture
d)Asbestos break into splinters or fibers.
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
8. Density
a)Density if the property of all matter that is the ratio of an object’s mass to its volume.
b)Many common minerals have densities between 2 and 5gm/cm3.
c)Some metallic metals have densities that are often greater than rock-forming minerals. For example Galena, and gold
d)Density can be used to determine the purity or identity of some minerals.
WHAT PROPERTIES CAN BE USED TO IDENTIFY MINERALS?
WHAT ARE SOME DISTINCT PROPERTIES OF MATTER?
1. Some minerals can be recognized by other distinctive properties.
a)Talc feels soapy
b)Graphite feels greasy
c)Metallic minerals, such as gold, silver and copper, can be shaped
d)Magnetite and hematite are magnetic
e)When a piece of transparent calcite is place over printed material, the lines appear double (double refraction)
f) Streaks of a few minerals that contain sulfur smell like rotten eggs
g)A droplet of hydrochloric acid will cause carbonate minerals, such as calcite, to fizz
WHAT ARE SOME DISTINCT PROPERTIES OF MATTER?
1.