1. Unit – 2
Mineralogy

2. A mineral:
is a naturally occurring inorganic crystalline solid
has an ordered internal arrangement of atoms
has specific physical properties that are either fixed or that vary within some defined range.
has a definite chemical composition that may vary within specific limits

3. Types of minerals Comman rock-forming minerals
(eg: feldspar,quartz,mica,kyanite etc)
Economic minerals (eg:hematite,galena,chrimite,magnesite etc)

4. Importance of mineralogy
As different rocks are used in different civil constructions so as a civil engineer we must be know to enable them to consider different rocks for different construction purposes. Knowledge of properties like strength, durability, and appearance of rocks can be assessed by only with the knowledge of minerals that forms rocks.

5. Different methods of study of minerals
Study of physical properties
Study of chemical properties
Study of optical properties
X-ray analysis

6. Study of Physical Properties of Minerals
Form
Colour
Streak
Luster
Fracture
Cleavage
Hardness
Specific gravity
Degree of transparency
Special Properties
Other Properties

7. Importance of Physical properties of minerals
Since every mineral possess different physical properties so it is easy to know about the mineral by knowing its physical properties. From the civil engineering point of view it is very important to know the physical properties of minerals to use them in different constructions.

8. 1. Form:
Form is nothing but the physical appearance of mineral. It I also called as structure of the mineral.
Tabular form: mineral occurs in the form of a flattened, square, rectangular shape with uniform thickness
Lamellar form: mineral appears as thin separable layers.
Bladed form: mineral appears as if composed of thin, flat, parts as it is cutted with blade.

9. Granular form: mineral appears in the form of densely packed grains.
Massive form: no definite shape for minerals.
Reni form: mineral appears with no. of overlapped kidney-shaped structures.
Bladed form
Granular form
Massive form
Reni form

10. 4. Lusture: It is the shining property of mineral. It is dependent on;
2. Colour: The colour of the any mineral is a light dependent property. Sometimes it is because of the presence of trace elements, sometimes due to composition.
3. Streak: It is the colour of mineral powder. Different minerals exhibit different streak most of them exhibit white colour.
4. Lusture: It is the shining property of mineral. It is dependent on;
The refractive index
The absorption capacity if light
The nature of reflecting surface

11. Typical lustures of minerals
Metallic: shines like a metal. Eg: galena
Vitreous: shines like a glass. Eg: quartz
Pearly: shines like a pearl. Eg: mica
Silky: shines like a silk. Eg: gypsum
Resinous: shines like a resin. Eg:opal
Greasy: shines like a grease. Eg: graphite
Dull: shine is almost absent. Eg: chalk.
Adamantine: shines like a diamond. Eg: diamond

12. Typical fractures of minerals
It is the nature of the randomly broken surface of a mineral. It is less useful property of mineral because most of the minerals shows same fracture.
Typical fractures of minerals
Even : broken surface is smooth and flat. Eg: chalk
Uneven: broken surface is irregular. Eg: most of the minerals.
Hackly: broken surface is irregular with separable layers. Eg: asbestos.
Conchoidal: broken surface shows concentric rings. Eg: opal
Sub-conchoidal; broken surface shows concentric rings with less curvature. Eg:agate

13. chalk
talc
biotite
opal

14. 6. Cleavage:
The definite direction or plane along which a mineral tends to break is called cleavage.

15. 7. Hardness:
It may be defined as the resistance offered by mineral to scratching.
Based upon the Moh’s scale of hardness minerals are arranged according to their hardness from 1 to 10.

16. Density types of minerals
8.Specific gravity(density):
Density of a mineral is defined as mass per unit volume of the mineral.
Density types of minerals
Low density sp.gravity<2.5
Medium density sp.gravity 2.5 to 3.5
High density sp.gravity>3.5

17. 9. Degree of transparency:
The property of the mineral to pass light through it.
They may be classified as,
Transparent
Translucent
opaque
10. Special properties: some minerals exhibit special properties.

18. Advantages of study of minerals by physical properties
Study of mineral in field it self.
Does not require any equipment
No need of chemicals
No loss or wastage of minerals
Quickest method
Cheapest, simplest and least tedious

19. Study of chemical composition
From definition minerals have its own distinctive chemical composition. If the composition is known it is easy to identify the mineral.
Study of optical properties
Making use of polarized light under crossed nicols, different optical properties of the minerals like colour, refractive index, total refraction etc. are studied.

20. Polarising microscope

21. X-ray analysis
It make use of the atomic structure of the mineral to identify them. X-rays are similar to light waves but have a much shorter wavelength.

22. Atomic structure of mineral by x-ray analysis
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