SHS Earth and Life Science | Lesson 3: MINERALS

Summary

This 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

• 📚 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.
• 🌏 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.
• ❌ Water and snowflakes are not considered minerals because they do not meet the criteria of being solid and crystalline, or are not naturally occurring.
• 🛠 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.
• 🔍 Five key characteristics help identify minerals: natural occurrence, inorganic nature, homogeneity, definite chemical composition, and crystalline structure.
• 🌟 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.
• 🎨 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.
• 📐 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.
• 🔬 Mineral classification is primarily based on chemical composition, with major groups including native elements, silicates, oxides, sulfates, sulfides, carbonates, and halides.
• 🏗️ 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.
• 🧪 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

00:00

📚 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.

05:01

🔍 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.

10:03

🌋 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.

Keywords

💡Minerals

Minerals are naturally occurring, inorganic, solid substances with an orderly crystalline structure and a definite chemical composition. They are the fundamental building blocks of rocks and are integral to the Earth's structure. In the video, minerals are discussed as the basis for understanding Earth's composition and their importance in conservation for future generations.

💡Rock-Forming Minerals

Rock-forming minerals are those that are abundant and common in the Earth's crust, making up large masses of rock. The script mentions that these minerals are essential to study as they contribute significantly to the formation of rocks and the geological processes of the planet.

💡Crystalline Structure

A crystalline structure refers to the orderly and repeating pattern in which the atoms of a mineral are arranged. This structure is a defining characteristic of minerals and is crucial for their identification. The script explains that minerals have an 'orderly crystalline structure,' which is a key aspect of their physical properties.

💡Luster

Luster is the quality and intensity of light that a mineral reflects. It can vary from metallic to non-metallic, such as vitreous or resinous, and helps in identifying minerals. The video script describes luster as one of the several properties that must be identified and defined to understand minerals better.

💡Hardness

Hardness is a measure of a mineral's resistance to abrasion or its ability to scratch other materials. The script introduces Friedrich Mohs' hardness scale, which ranges from 1 to 10 and is used to compare the hardness of different minerals, with talc being the softest and diamond the hardest.

💡Crystalline Habit

Crystalline habit is the external shape of a crystal or group of crystals as they grow in open spaces. It reflects the internal structure of the atoms and ions within the crystal. The script uses the term to describe how the natural shape of a mineral is formed before any cleavage or fracture occurs.

💡Color and Streak

Color is the natural appearance of a mineral, but it can be affected by impurities and weathering. Streak, on the other hand, is the color of a mineral when it is in powdered form, which is more diagnostic for identification. The script emphasizes that streak is a more reliable property for mineral identification compared to color.

💡Cleavage

Cleavage is the property of minerals to break along specific planes of weakness, forming smooth, flat surfaces. This property is due to the weak atomic bonding in certain areas of the mineral's structure. The script explains cleavage as distinct from crystalline habit and uses it as a criterion for mineral identification.

💡Specific Gravity

Specific gravity is the ratio of the density of a mineral to the density of water and indicates how much heavier the mineral is compared to an equal volume of water. The script mentions specific gravity as a way to compare the weight of minerals and as a characteristic used in mineral identification.

💡Diaphaneity

Diaphaneity refers to the ability of a mineral to allow light to pass through it, which is affected by the mineral's chemical makeup. The script describes diaphaneity as a property that can be used to identify minerals, with examples of transparent, translucent, and opaque minerals provided.

💡Mineral Classification

Mineral classification is the categorization of minerals based on their chemical composition. The script outlines several classes, including native elements, silicates, oxides, sulfates, sulfides, carbonates, and halides, and explains that these classifications help in understanding the variety and properties of minerals.

💡Silicates

Silicates are minerals containing silicon and oxygen, which are the two most abundant elements in the Earth's crust. They form the silicon-oxygen tetrahedron, which is the fundamental building block of silicate minerals. The script highlights that over 90% of rock-forming minerals belong to this group, emphasizing their prevalence and importance.

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