Lithology

In other words the study of rocks and their formation is called lithology.
It helps in understanding and describing the physical characteristics of rock units such as their color, grain size, texture or composition.

Lithology also helps in understanding porosity, permeability, water saturation, etc., and other petrophysical properties of rocks.

Lithology can be either a detailed description or a summarized description on the gross physical characteristics of the rock.
Sometimes lithology is also meant to be the type or the composition of rock such as limestone or sandstone.
The following items are observed under lithology for the details on reservoir rocks:

• Pore structure
• Diagenetic and depositional history of rocks
• Mineralogy

The naming of rocks in lithology is based on the rock types.
There are 3 major rock types as per lithology, they are:

• Sedimentary rocks
• Metamorphic rocks
• Igneous rocks