minerals, classification of minerals, properties of minerals and few examples

1. Mineralogy

2. Mineralogy and Petrology
● Properties of minerals
● Identification of minerals based on properties
● Metamorphic petrology
● Sedimentary petrology
● Igneous petrology

3. Minerals
● Naturally occurring inorganic substance which is crystalline in
structure and having definite chemical composition and atomic
structure.
● Till now more than 2000 minerals have been studied.
● Mineral formation
i. CRYSTALLIZE FROM MAGMA or LAVA: solidification of liquid
magma/lava to solid with a definite internal arrangement of
atoms into a regular repeating pattern
ii. PRECIPITATE FROM SOLUTION: dissolved minerals come out of
solution (water) to form solids

4. Mineralogy
● Branch of geology which deals
with the Study of Minerals with
respect to their physical and
chemical properties.
● The study has been divided into 3
parts
a. Part 1 - Physical Properties
b. Part 2- Crystallography
c. Part 3 - Mode of formation

5. How Minerals are formed ?
● Cooling of magma (hot, liquid rock and minerals inside the earth
(from the mantle)
1. Fast Cooling = No Crystals (mineraloids)
2. Medium Cooling = SMALL crystals
3. Slow Cooling = LARGE crystals
● Elements dissolved in liquids (usually water) will reform into
crystals as the water evaporates and the dissolved elements
recrystalize.

6. Physical properties
i. Color
ii. Streak
iii. Luster
iv. Hardness
v. Cleavage
vi. Fracture
vii. Tenacity
viii. Form
ix. Specific gravity

7. Cont.., Physical properties
1. Color
● Light dependent property
● Appearance of an object when subjected to light.
● Colour of a mineral is a colour which is not absorbed by it from white light.
● On basis of colour,minerals are classified into 3 types
a. Idiochromatic- Constant colour (Metallic minerals)
b. Allochromatic - variable colour
c. Pseudochromatic - False colour ( Simultaneous reflection and
refraction)

8. Cont.., Physical properties
2. Streak
● Colour of a mineral which is obtained on rubbing or scratching on a
porcelain plate.
● Porcelain plate is termed as streak plate.

9. Cont.., Physical properties
3. Lustre
● Intensity of reflection of light from mineral
from surface.
● Factors influencing
○ Refractive index
○ Absorption capacity of minerals
○ Nature of reflecting surface
● It can be explained based on following terms
○ Metallic
○ Adamantine
○ Vitreous
○ Pearly
○ Silky
○ Resinous
○ Dull or earthy

10. Cont.., Physical properties
4. Hardness
● Resistance offered by the
mineral against external
deformation due to rubbing,
scratching or indentation.
● In the year 1822 F.Mohr given
quantitative measure as scale of
hardness which is called as
Hardness number.

11. Cont.., Physical properties
5. Cleavage
● It plane is a plane of structural
weakness along which a mineral is
likely to split smoothly. Cleavage thus
refers to the splitting of a crystal
between two parallel atomic planes.
● A mineral may have cleavage in 1, 2 or
3 directions
● In general cubic, rhombohedral,
prismatic, basal and octahedral
cleavage

12. Cont.., Physical properties
6. Fracture
● Broken surface of mineral
other than that of cleavage.
● Common types of fracture are
a. Even (smooth and flat)
b. Uneven (irregular )
c. Conchoidal (concentric rings)
d. Splintry (Woody fracture)
e. Hackly ( highly irregular with
sharp and fine edges)
f. Earthy ( Smooth, soft and
porous)

13. Cont.., Physical properties
7. Tenacity
● Behaviour of the mineral towards forces which tend to
break,bend or cut.
a. Sectile - can be cutted with knife
b. Malleable - can be flattened by hammer
c. Brittle
d. Flexible- can be bent
e. Plastic and elastic

14. Cont.., Physical properties
8. Form (structure )
● Physical shape of the mineral is
expressed in the form of structure.
● Common structural forms are
a. Tabular
b. Elongated
c. Lamellar
d. Foliated
e. Fibrous
f. Radiating
g. Granular
h. Globular
i. Reniform
j. Mammillary

15. Cont.., Physical properties
9. Specific gravity
● Mass per unit volume of substance.
● In minerology specific gravity is defined as ratio of density of
mineral to that of water at 4 °C.
● Minerals is primarily based on
1. Composition
2. Atomic constitution

16. Cont.., Physical properties
Miscellaneous properties
1. Magnetism (Ex: Magnetite )
2. Electricity (Ex : Quartz )
3. Fluorescence (Ex : Fluorite )
4. Fusibility

17. Minerals are classified in 2 groups
1. Silicates
a. Silica group
b. Mica group
c. Feldspar group
d. Amphibole group
e. Pyroxene group
2. Non silicates

18. PROPERTIES OF MINERALS
1. ORTHOCLASE ( KAlSi3
O8
)
1. Color -White, gray, pink, reddish, yellow, green, colorless
2. Streak -White
3. Luster -Vitreous, pearly on cleavage faces
4. Hardness - 6-6.5
5. Cleavage - 2 directions at 90 degree angle.
6. Fracture- even
7. Form - Tabular
8. Specific gravity - 2.56- 2.58

19. Cont.., ORTHOCLASE
Uses
1. Ceramics
2. Glass manufacturing
3. Gemstones
Occurrence
Igneous rock ( especially granite)

20. 2. Augite(Ca,Na)(Mg,Fe,Al)(Si,Al)2
O6
1. Color -occurs in various colours usually Dark
green, black, brown
2. Streak -White to gray to very pale green.
3. Luster -Vitreous
4. Hardness - 5-6
5. Cleavage - prismatic at 110 degree.
6. Fracture- uneven
7. Form - Tabular
8. Diaphaneity- Usually translucent to opaque.
Rarely transparent.
9. Specific gravity - 3.25- 3.55
Occurrence
Ferro magnetism mineral of igneous rocks.

21. 3. Hornblende
1. Color -Black to dark green or
brown
2. Streak -greenish tint,
gray-white, white, colorless
3. Luster -Vitreous
4. Hardness - 5.5-6
5. Cleavage - Imperfect at 56°
and 124
6. Fracture- uneven
7. Form -granular
8. Diaphaneity-Translucent to
nearly opaque.
9. Specific gravity - 3-3.47

22. Uses of Hornblende
1. Hornblende is the most abundant mineral in
a rock known as amphibolite, which has a
large number of uses. It is crushed and used
for highway construction and as railroad
ballast.
2. The highest quality pieces are cut, polished,
and sold under the name "black granite" for
use as building facing, floor tiles,
countertops, and other architectural uses
Occurance
Igneous rocks and metamorphic rocks.

23. 4. Pyroxenes(Ca, Mg, Fe(SiO3)2)
1. Color -dark green to black,
brown
2. Streak -greenish tint,
gray-white, white, colorless
3. Luster -non metallic
4. Hardness - 5-6
5. Cleavage - 2 perfect at 87°
almost right angles
6. Fracture- uneven
7. Form -granular
8. Diaphaneity-Translucent to
nearly opaque.
9. Specific gravity - 3.2 to 3.9

24. Cont.., Pyroxenes(Ca, Mg, Fe(SiO3)2)
Uses
1. Gem materials, but only in rare instances
when they have attractive color and clarity.
Jadeite, diopside, and spodumene are the
most important pyroxene gem materials.
2. secondary constituents of many rocks used
to make crushed stone dimension stone, and
architectural stone.
Occurrence
Igneous rocks and metamorphic rocks.

25. Mica group
Micas are classified into 2 groups
1. Light micas
a. Muscovite
b. Paragonite
c. Lepidolite
2. Dark micas
a. Biotite
b. Phlogopite
c. Zinnwaldite

26. 5. Muscovite( KAl2
(Si3
AlO10
)(OH)2
)
1. Color -colourless in thin sheet but
pale yellow in appearance
2. Streak -colorless
3. Luster - pearly to vitreous
4. Hardness -2.5-3
5. Cleavage - Perfect
6. Fracture- uneven
7. Form -Sheet
8. Diaphaneity-Transparent to
translucent
9. Specific gravity - 2.7-3.1

27. Cont.., Muscovite
Uses
● It acts as a filler and extender, provides a smoother consistency, improves
workability.
● In the paint industry, ground mica is used as a pigment extender.
● Sheet mica is used principally in the electronic and electrical industries.
● Electrical insulators in electronic equipment, thermal insulation, gauge
“glass”, dielectrics in capacitors, decorative panels in lamps and windows,
insulation in electric motors and generator armatures, field coil
insulation.
Occurrence
Igneous rocks and metamorphic rocks.

28. Thank you