This document discusses the physical properties of rocks. It defines a rock as an aggregate of mineral particles that can be sedimentary, metamorphic, or igneous. Physical properties describe the performance of rocks under different conditions and help classify rocks. These properties include specific gravity, density, porosity, permeability, and electrical/thermal conductivity. Mineralogical composition, structure, and texture also influence the physical properties of a rock. The document provides examples of common rock-forming minerals and explains how properties like density and specific gravity are measured and used to characterize rocks.

1. Physical Properties of Rocks
Luqman Ahmed
Department of Earth Sciences
University of Sargodha, Sargodha,
Pakistan

2. Physical Properties of Rocks
Rock
• A Rock material is an aggregate of mineral particles
• Sedimentary, metamorphic, igneous rocks
Physical Properties
• The performance of rock, under a particular condition
depends upon physical and mechanical properties of rock
materials
• The physical properties may be known as index properties,
which describes the rock material and helps in classifying
them
Mechanical Properties
• The mechanical properties may be known as strength
properties and they will give an information about the
performance of rock materials, when subjected to a particular
loading system.

3. Physical Properties of Rocks
• Mineralogical composition, structure, and texture;
• Specific gravity G
• Unit weight/ Density
• Void ratio e
• Porosity n
• Moisture content w or m
• Degree of saturation, S
• Coefficient of Permeability K
• Electrical and Thermal Properties
• Swelling
• Anisotropy
• Durability

4. MINERALOGICAL COMPOSITION
Main Minerals in all three types of rocks
(Sedimentary, Metamorphic and igneous rocks)
• Quartz
• Feldspar
• Mica
• Homblende (Amphiboles)
• Pyroxene
• Olivine
• Calcite
• Kaolin, and
• Dolomite
Significance of Mineral Composition
• Physical Properties
• Mechanical Properties
• Hard rocks/ soft rocks

5. ROCK STRUCTURE & TEXTURE
The makeup of rocks from minerals and mineral aggregates.
Texture
Texture is determined by the dimensions, shape, and interrelationships of
the minerals.
 Grain size distribution
 Fine grained, medium grained, coarse grained
 Uniformly grained, well-graded, etc.
Porosity, Permeability, density, etc.
Structure
structure depends on the general features and spatial arrangement of the
larger
components of the rock
 Massive (No discontinuities), lamination, bedding, shearing, etc.

6. DENSITY, UNIT WEIGHT & SPECIFIC GRAVITY
Density
Mass per unit volume.
𝜌 =
𝑚
𝑉
 Units: g/cm3 , Kg/m3
 Dry Density,
 Bulk Density
 Standard Density
What density gives?

7. DENSITY, UNIT WEIGHT & SPECIFIC GRAVITY
Unit weight
Weight per unit volume
 𝛾 =
𝑊
𝑉
=
𝑚𝑔
𝑉
= 𝜌𝑔
 Units: kN/m3
 Water 9,800 N/ m3 or 9.81 kN/m3

 Specific gravity
 Ratio of the density of solids to the density
of water.
 𝐺 =
𝜌𝑠
𝜌𝑤
 SP is also called Relative Density