1. Alzaiem Alazhari University
Faculty of engineering
Civil Engineering Department
Eng. Majzoob Mohammed Arbab
06 September 2022
الرحيم الرحمن هللا بسم
Engineering Geology
Mineralogy
2. Minerals
• are 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. Importance of mineralogy
As different rocks are used in different civil constructions so
as a civil engineers we must be able 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.
4. • Study of physical properties
• Study of chemical properties
• Study of optical properties
• X-ray analysis
Methods used for studying minerals
5. • Form
• Color
• Streak
• Luster
• Fracture
• Cleavage
Study of Physical Properties of Minerals
• Hardness
• Specific gravity
• Degree of transparency
• Special Properties
• Other Properties
6. 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.
7. Form
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 cut with blade.
8. Form
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.
9. Physical properties of minerals
2. Color: The color 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 color of mineral powder.
Different minerals exhibit different streak most of them exhibit
white color.
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.
10. Physical properties of minerals
5. Fracture:
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 witless curvature.
Eg:agate
11. Physical properties of minerals
6. Cleavage:
The definite direction
or plane along which
a mineral tends to
break is called
cleavage.
12. Physical properties of minerals
7. Hardness:
It may be defined as the resistance offered by mineral to scratching.
Based upon the Mohr's scale of hardness minerals are arranged
according to their hardness from 1 to 10.
13.
14. Physical properties 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
9. Degree of transparency:
The property of the mineral to pass light through it. They may be classified as,
•Transparent
•Translucent
•opaque
15. Chemical properties of minerals
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, different optical properties of the
minerals like color, refractive index, total refraction etc. are studied.
16. 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.
