SHS Earth and Life Science | Lesson 3: MINERALS
Summary
TLDRThis educational script introduces students to the world of minerals, emphasizing their importance as the building blocks of rocks and the earth's crust. It defines minerals by their natural occurrence, inorganic nature, crystalline structure, and chemical composition. The lesson covers identifying minerals through properties like luster, hardness, and streak, and delves into mineral classification, highlighting the abundance of silicates. It also discusses the significance of understanding minerals' interactions within the earth's systems for a comprehensive study of geology.
Takeaways
- π Minerals are naturally occurring, inorganic, solid substances with an orderly crystalline structure and a definite chemical composition, serving as the basic building blocks of rocks.
- π Minerals are integral to the Earth's systems and interact with other parts of the planet, making their study essential for understanding Earth's processes.
- β Water and snowflakes are not considered minerals because they do not meet the criteria of being solid and crystalline, or are not naturally occurring.
- π Products made from minerals are part of our daily lives, including graphite in pencils, halite in salt, and various minerals in electronic devices and infrastructure.
- π Five key characteristics help identify minerals: natural occurrence, inorganic nature, homogeneity, definite chemical composition, and crystalline structure.
- π Luster, hardness, and crystalline habit are among the properties used to distinguish minerals, with the Mohs hardness scale being a common tool for measuring mineral resistance to scratching.
- π¨ Color and streak are important properties for mineral identification, but streak, the color of a mineral in powdered form, is more reliable due to variations in color caused by impurities and weathering.
- π Cleavage, specific gravity, and transparency are additional properties that help in identifying minerals, with cleavage referring to the tendency of minerals to break along planes of weakness.
- π¬ Mineral classification is primarily based on chemical composition, with major groups including native elements, silicates, oxides, sulfates, sulfides, carbonates, and halides.
- ποΈ Silicates, composed of silicon and oxygen, are the most abundant mineral group in the Earth's crust, making up over 90% of rock-forming minerals.
- π§ͺ The elements oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium make up almost 99% of the Earth's crust, highlighting their prevalence in mineral composition.
Q & A
What are the basic criteria for a substance to be classified as a mineral?
-A substance must be naturally occurring, inorganic, solid with an orderly crystalline structure, and have a definite chemical composition.
Why is water not considered a mineral?
-Water is not considered a mineral because it is not solid and lacks a crystalline structure.
Can a snowflake be classified as a mineral according to the given definition?
-No, a snowflake is not a mineral because it is not naturally occurring; it is a product of water freezing in the atmosphere.
What are some everyday products made from minerals?
-Products such as wooden pencils containing graphite, table salt containing halite, and electronic devices containing minerals like gold and silver are made from minerals.
What are the five characteristics used to identify minerals?
-The five characteristics are: naturally occurring, inorganic, homogeneous solid with a definite volume and rigid shape, definite chemical composition, and orderly crystalline structure.
What is the Mohs scale of hardness, and who designed it?
-The Mohs scale of hardness is a scale that measures the scratch resistance of minerals, ranging from 1 to 10, based on the ability of a harder mineral to scratch a softer one. It was designed by German geologist and mineralogist Friedrich Mohs in 1812.
What are the advantages and disadvantages of using the Mohs scale of hardness?
-Advantages include its ease of use and convenience for field geologists, as it can be performed anywhere with sufficient light. Disadvantages are its qualitative nature, making it non-quantitative and not suitable for accurately testing the hardness of industrial materials.
What is the difference between a mineral's luster and its color?
-Luster refers to the quality and intensity of reflected light exhibited by a mineral, while color is the hue seen by the eye and can be influenced by impurities and geological processes.
Why is streak a more reliable property for mineral identification than color?
-Streak is the color of a mineral in powdered form and is inherent to most minerals, making it more reliable for identification. Color can vary due to impurities and weathering, making it less reliable.
What is the difference between a mineral's crystalline habit and its cleavage planes?
-Crystalline habit refers to the external shape of a crystal or group of crystals as they grow in open spaces, reflecting the internal structure. Cleavage planes are specific planes of weakness along which some minerals break to form smooth, flat surfaces.
Which mineral group is most abundant in the Earth's crust, and what elements are they composed of?
-Silicates are the most abundant mineral group in the Earth's crust, composed mainly of silicon and oxygen, forming the silicon-oxygen tetrahedron.
How does the specific gravity of a mineral relate to its density and the density of water?
-Specific gravity is the ratio of the density of a mineral to the density of water. It indicates how many times more the mineral weighs compared to an equal volume of water, with water having a specific gravity of one.
What are the main elements that make up the majority of the Earth's crust, and what type of minerals are they associated with?
-The main elements are oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium. They are primarily associated with silicates, which are the most abundant minerals in the Earth's crust.
Outlines
π Introduction to Minerals and Their Conservation
The script introduces the topic of minerals, emphasizing the importance of conservation for future generations. It defines minerals as naturally occurring, inorganic solids with a crystalline structure and a definite chemical composition. The lesson aims to help students understand how minerals interact with the Earth's systems and their role in forming rocks, soil, and the Earth's mantle. Common misconceptions about what constitutes a mineral are addressed, and everyday products made from minerals are highlighted. The script also outlines the five key characteristics used to identify minerals.
π Mineral Identification and Properties
This paragraph delves into the properties that aid in mineral identification, such as luster, hardness, crystalline habit, color, streak, and specific gravity. It explains the Mohs scale of hardness and its advantages and limitations. The paragraph also discusses other mineral properties like cleavage, transparency, and tenacity, and how they differ from one another. The classification of minerals based on their chemical composition is introduced, highlighting the abundance of silicates in the Earth's crust and the role of key elements like oxygen, silicon, aluminum, and iron.
π Rock-Forming Minerals and Earth's Crust Composition
The final paragraph focuses on rock-forming minerals, their characteristics, and the process of identifying them. It poses questions to engage the students in the evaluation of the information provided, such as distinguishing between mineral groups and understanding the prevalence of silicates in the Earth's crust. The paragraph also explores the concept of streak as a reliable identifier compared to color, the difference between habit and cleavage, and the possibility of minerals having a prismatic habit without cleavage, using quartz as an example. The summary concludes with an assignment for students to complete further learning tasks.
Mindmap
Keywords
π‘Minerals
π‘Rock-Forming Minerals
π‘Crystalline Structure
π‘Luster
π‘Hardness
π‘Crystalline Habit
π‘Color and Streak
π‘Cleavage
π‘Specific Gravity
π‘Diaphaneity
π‘Mineral Classification
π‘Silicates
Highlights
Lesson focuses on understanding minerals and their conservation for future generations.
Minerals are naturally occurring, inorganic, solid substances with a crystalline structure and definite chemical composition.
Minerals are the basic building blocks of rocks and are essential for a thorough study of the Earth.
Water and snowflakes are not considered minerals due to their lack of crystalline structure and natural occurrence, respectively.
Products made from minerals are used daily, such as graphite in pencils and halite in salt.
Minerals can be identified by five characteristics: naturally occurring, inorganic, homogeneous solid, definite chemical composition, and orderly crystalline structure.
Luster, hardness, crystalline habit, color, and streak are properties used to identify minerals.
The Mohs scale of hardness is a qualitative measure of a mineral's scratch resistance, ranging from 1 to 10.
Minerals can be categorized by their chemical composition, such as native elements, silicates, oxides, sulfates, sulfides, carbonates, and halides.
Silicon and oxygen are the most abundant elements in the Earth's crust and form the basis of silicate minerals.
Streak is a more reliable property for mineral identification than color due to its consistency regardless of impurities or weathering.
Crystal habit and cleavage are distinct properties; habit is the natural shape of the mineral, while cleavage is the plane of weakness along which it breaks.
Specific gravity indicates the weight of a mineral compared to an equal amount of water.
Diaphaneity, or transparency, is affected by the chemical makeup of the mineral and its ability to allow light to pass through.
Minerals can exhibit various reactions to stress, such as brittleness, malleability, ductility, flexibility, and sectility.
An opaque mineral with a black streak and high density is likely to be metallic due to its weight and dark streak.
Quartz is an example of a mineral that can have a prismatic habit without cleavage, breaking only by fracturing.
Rock-forming minerals are common and abundant, making up large masses of rock, such as quartz, feldspar, and mica.
Transcripts
hello dear students our lesson for today
is all about minerals
in this lesson you should be able to
make a plan that the community may use
to conserve and protect its resources
for future generations
and identify common rock forming
minerals using their physical and
chemical properties
mineral is a naturally occurring not
man-made or machine-generated
inorganic not a by-product of living
things solid with an orderly crystalline
structure and a definite chemical
composition
minerals are the basic building blocks
of rocks
minerals make up the rocks beneath your
feet the soil that supports plants
and the deep rock of earth's mantle any
thorough study of earth must include an
understanding of minerals
but it is not sufficient to study
minerals isolated from the rest of the
planet
rather we can learn more by observing
the ways that minerals interact with
other earth systems
before we continue let's answer some
questions
firstly do you consider water a mineral
if you answered no
you're right because water is not solid
in crystalline
let's try another question how about
snowflake or two bites
are these minerals well two vice is not
a mineral
because it is not naturally occurring
but a snowflake possesses all the
properties under the definition of a
mineral
if you guessed all the answers correctly
great job
but if you didn't worry not because as
we go through our lesson
you will learn everything about minerals
and be able to identify if something is
a mineral
minerals are not always hard to find
actually
we are using these products made from
minerals daily
graphite is the mineral used in wooden
pencil halite is the mineral found in
salt
your cell phone is made up of different
minerals like gold and silver
the cars that we drive the roads that we
travel the building that we live in
are some examples of products derived
from minerals
there are five characteristics of
minerals that we can use to identify
them
first naturally occurring or a product
of earth's natural processes
second inorganic or it must be product
of earth's physical processes
third homogeneous solid minerals should
have definite volume and rigid shape
fourth definite chemical composition it
must be represented by a chemical
formula
and fifth orderly crystalline structure
the atoms of minerals are arranged in an
orderly and repeating pattern
there are several different mineral
properties which must be identified and
defined
first we have luster it is the quality
and intensity of reflected light
exhibited by the mineral
it can be metallic generally opaque and
exhibit a resplendent shine similar to a
polished metal
or non-metallic vitreous glassy
adamantine brilliant diamond-like
resinous
silky pearly dull earthy greasy among
others
next hardness it is a measure of the
resistance of a mineral not specifically
surfaced to abrasion
hardness scale is designed by german
geologist mineralogist friedrich moss in
1812.
the moss scale of hardness measures the
scratch resistance of various minerals
from a scale of 1 to 10
based in the ability of a harder
material mineral to scratch a softer one
the moss scale of hardness measures the
scratch resistance of various minerals
from a scale of 1 to 10
based in the ability of a harder
material mineral to scratch a softer one
however there are pros and cons to using
the moss scale
pros are the test is easy the test can
be done
anywhere anytime as long as there is
sufficient light to see scratches
the test is convenient for field
geologists with scratch kits who want to
make a rough identification of minerals
outside the lab
while the cons are the scale is
qualitative not quantitative
the test cannot be used to accurately
test the hardness of industrial
materials
you can see on the picture on the right
that the moss hardness scale is
organized from the softest to the
hardest
for the softest one we have talc
followed by gypsum
calcite fluorite apatite feldspar
quartz topaz corundum and the hardest is
diamond
the third property of minerals is its
crystalline habit
the external shape of a crystal or
groups of crystals is displayed or
observed as these crystals grow in open
spaces
the form reflects the supposedly
internal structure of atoms and ions of
the crystal mineral
it is the natural shape of the mineral
before the development of any cleavage
or fracture
examples include prismatic tabular
bladed
platy reniform and equine a mineral that
do not have a crystal structure is
described as amorphous
next we have color a lot of minerals can
exhibit same or similar colors
individual minerals can also display a
variety of colors resulting from
impurities and also from some geologic
processes like weathering
examples of coloring quartz can be pink
which is called rose quartz
amethyst is purple citrine is orange and
colorless quartz
next streak streak is the mineral's
color in powdered form
it is inherent in almost every mineral
and is a more diagnostic property
compared to color
note that the color of a mineral can be
different from its streak
examples of streak pyrite exhibits gold
color but has a black or dark gray
streak
the crystals form also defines the
relative growth of the crystal in three
dimensions which include the crystal's
length width and height
next cleavage cleavage is the property
of some minerals to break along specific
planes of weakness to form smooth flat
surfaces
planes exist because the bonding of
atoms making up the mineral happens to
be weak in those areas
when minerals break evenly in more than
one direction cleavage is described by
the number of cleavage directions
the angle at which they meet and the
quality of cleavage
cleavage is different from habit the two
are distinct
unrelated properties although both are
dictated by crystal structure
crystal habit forms as the mineral is
growing relying on how the individual
atoms in the crystal come together
cleavage meanwhile is the weak plane
that developed after the crystal is
formed
next specific gravity it is the ratio of
the density of the mineral and the
density of water
this parameter indicates how many times
more the mineral weighs compared to an
equal amount of water
whose specific gravity is one for
example
a bucket of silver with specific gravity
10 would weigh 10 times more than a
bucket of water
next diaphania t or the amount of
transparency
it is the ability to allow light to pass
through it this is affected by chemical
makeup of the mineral sample
as you can see on the picture the
crystal is able to pass light
other properties of minerals include the
following
tenacity describes the mineral's
reaction to stress
brittleness a mineral turns into powder
malleability a mineral can be flattened
by pounding with a hammer
ductility a mineral can be stretched
into wire
flexible but inelastic minerals are bent
but they remain in the new position
flexible and elastic minerals are bent
and they bring back to their original
position
sectility is the ability of a mineral to
be cut into thin pieces with a knife
minerals like many other things can also
be categorized
the most stable and least ambiguous
basis for classification of minerals is
based on their chemical compositions
we have the native elements gold bismuth
and diamond
silicates quartz olivine and talc
oxides hematite magnetite and chromite
sulfates gypsum barite and anhydrite
sulfides p right galena and bornite
carbonates calcite dilomite and
malachite
lastly halides chlorine chlorine
and halite the elements listed below
comprise almost 99 percent of the
minerals making up the earth's crust
namely oxygen silicon aluminum
iron calcium sodium potassium
magnesium and all the other elements
silicates are minerals containing the
two most abundant elements in the
earth's crust
namely silicon and oxygen when linked
together
these two elements form the silicon
oxygen tetrahedron
the fundamental building block of
silicate minerals
over 90 of rock-forming minerals belong
to this group
oxides are minerals composed of oxygen
anion o2 combined with one or more metal
ions
sulfates are minerals containing sulfur
and oxygen in the form of the so4 anion
sulfides are minerals containing sulfur
in a metal
some sulfides are sources of
economically important metals such as
copper
lead and zinc carbonates
minerals containing the carbonate anion
combined with other elements
native elements are minerals that form
as individual elements
we have metals and inter metals minerals
with high thermal and electrical
conductivity
typically with metallic luster low
hardness
semi-metals minerals that are more
fragile than metals and have lower
conductivity
and nonmetals non-conductive sulfur
diamond
halides are minerals containing halogen
elements combined with one or more
metals
for the evaluation let us answer the
following
summarize the different characteristics
that define a mineral
answer inorganic naturally occurring
crystalline
solid and must have a consistent
chemical composition
which among the following mineral groups
if any contain
silicon halides carbonates or sulfides
explain answer none the identified
mineral groups are non-silicates
which is more abundant in the earth's
crust silicates or all the other mineral
groups combined
explain answer silicates
silicon and oxygen are the main
components of silicates and these are
the two most abundant elements in the
earth's crust
fourth an unknown opaque mineral has a
black streak and has a density of 18
grams per cc
is the mineral metallic or non-metallic
answer the mineral is more likely to be
metallic because it is opaque and
metallic minerals are usually heavy and
with dark streaks
how does streak differ from color and
why is it more reliable for rock
identification
answer streak is the color of a mineral
in powdered form
it is more reliable because it is
inherent to most minerals
color is not reliable because a mineral
can be formed with varieties of color
and effect of impurities and weathering
differentiate between habit and a
cleavage plane
answer habit is the external shape of a
crystal that is developed during the
formation of the mineral
a cleavage plane is a plane of weakness
that may develop after the crystal
formation
7. is it possible for a mineral to have
a prismatic habit without having any
cleavage
why or why not if yes give an example
answer yes the prismatic habit is
simultaneously developed while the
mineral is growing
during the process there is no
repetitive plane of weakness being
created which makes the mineral break
only by fracturing
an example of this scenario is quartz
define rock forming mineral and give
three examples
answer a rock forming mineral is a
mineral that is common and abundant in
the earth's crust
one making up large masses of rock
that's all for today i hope that you
learned all about minerals
for your activity answer the following
on your notes
learning task 5 page 16 learning task 6
page 17 to 19 learning task 7
page 24 to 25 and page 27
have a nice day
Browse More Related Video
5.0 / 5 (0 votes)