Physical Properties of Minerals 2015

8/19/2019 Physical Properties of Minerals 2015

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Atoms

Atoms

–

basic building blocks for all earth

materials; consist of 3 basic components:

protons, neutrons, electrons


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Atoms combine to form

Elements

Elements

–

fundamental component that

can not be broken down into other

substances by ordinary chemical

processes

Elements combine to form minerals


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General Facts About Minerals

2,000 + minerals have been identified

A few are “native elements”

--

made of

only one element, such as sulfur, gold.

copper, and graphite (carbon)

Most are compounds, especially the

silicate group (Si, O).

Other important groups are oxides,

carbonates, and sulfides.


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Mineral Criteria

1. Crys tal l ine so l id

–

atoms have speci f ic

arrangement or c rys tal st ruc ture

2. Natu ral ly occurr ing

–

no t manufactured

3. Have a def in i te chemical compos i tion

–

may be a sing le element o r combinat ion

4. Inorganic

–

minerals not made by l iv ing

th ings (org anic )


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MINERAL FORMATION

CRYSTALLIZE FROM MAGMA or LAVA

solidification of liquid magma/lava to solid

with a definite internal arrangement of

atoms into a regular repeating pattern

PRECIPITATE FROM SOLUTION

dissolved minerals come out of solution

(water) to form solids


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Physical Properties of Minerals

1- Optical PropertiesColor

Streak

Luster

Diaphaneity

2- Cohesive Properties

Hardness

CleavageParting

Fracture

Tenacity

3- Sense Properties

Touch

Odour

Teste

4- Specific Gravity

5- Other Properties such as:

Magnetism

Electricity

Radioactivity

FusibilitySolubility


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Minerals are identified by their

Physical Properties

Crystal Form – determines physical properties

Color

Streak

Luster – metallic, non-metallic

Hardness – Mohs Hardness Scale (1-10)

Cleavage

Fracture

Acid Test for carbonate minerals


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A mineral’s physical properties

are controlled by its internal

arrangement of atomsregularly repeating, orderly pattern


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The most common crystalline

structure

Silica-oxygen tetrahedron – basic

building block for silicate minerals


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Silica tetrahedron combine

several different ways

Five major types of

silicate minerals

based on their

structure A) Isolated tetrahedron

B) Single chain

C) Double chainsD) Sheet silicates

E) 3-D framework

silicates


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Minerals can have the same chemical composition

(Carbon) but different physical properties because

of their crystal structure

Diamond Graphite

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COLOR

Color is not usually a definitive property of

a mineral.

Some minerals have characteristics colors

Others vary due to chemical differences or

impurities (atoms mixed inside the main

elements)

However most minerals have a variety of

colors.


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Some Colors of Quartz


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Varieties of Hematite – all same color streak

HARDNESS

Mi l’ i t t


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HARDNESS – Mineral’s resistance to

scratching or abrasion. Minerals with higher

numbers will scratch minerals below


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LUSTER – Does this look like it could

be made from a hard metal?

Describes how light reflects off the surface

Categories: Metallic or Non-metallic

Metallic – luster of metal – shines like a hard metal

(light does not penetrate)

Many non-metallic minerals are SHINY because theyare transparent or semi-transparent

Non-metallic: vitreous or glassy; silky; pearly; greasy; waxy,dull; earthy


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Examples of metallic luster


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Pyrite (FeS2)

Galena (PbS)

More Examples of Metallic Luster

PYRITE

GALENA


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Example of non-metallic luster

Vitreous--quartz


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Example of non-metallic luster

Silky--example plagioclase feldspar


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Non-metallic and metallic luster –

earthy hematite – metallic hematite


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Cleavage and Fracture

Some minerals split along flat surfaces(called cleavage planes) when struck

hard--this is called mineral cleavage Other minerals break unevenly along

rough or curved surfaces--this is calledfracture

A few minerals have both cleavage andfracture ( mica )


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FLUORITE

HALITE

Halite (NaCl)

Fluorite (CaF2)

Cleavage – due to weak bonds in

the crystal structure


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Cleavage

BIOTITEMUSCOVITE


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Rose Quartz – Conchoidal Fracture


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Conchoidal Fracture - Quartz

Obsidian


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Acid Test for Carbonates

Special Characteristics:

Carbonates react with dilute HCl and other

acids by fizzing or bubbling (releasing

CO2 gas)


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Common uses include: Use back

page of ESRT for this information

Aluminum--packaging, transport, building

Beryllium--gemstones, fluorescent lights

Copper --electric cables, wires, switches

Feldspar --glass and ceramics

Iron--buildings, automobiles, magnets

Calcite--toothpaste, construction

Documents

Physical Properties of Minerals 2015