Concepts Of Geology

General Introduction:

Geology is a major branch of earth science and includes the long-term evolution of the Earth’s atmosphere, surface, and life, including plate tectonics and mountain formation, volcanoes, and earthquakes. The long-term evolution of the Earth’s atmosphere, surface, and life. Geology is quite socially relevant due to the growing demand for resources, exposure to increasing natural risks, and changing climate.

image 121



Geology is the science dedicated to the study of the earth’s surface. It discusses the study of the earth’s surface, composition, structure, and origin. We also study the inhabitants of the features of the earth, known as the term geology.

Branches Of Geology

We can be classified several branches of geology, such as:


Petrology is the study of all types of rocks, their origin, composition, and structure.


Mineralogy is the study of minerals, their origin, composition, composition, appearance, stability, etc.

Physical Geology:

Physical geology studies the work of natural processes that cause changes on the earth’s surface.


stratigraphy is indicated by strata (rock layer) of sedimentary strata and classification.

Structural Geology:

It deals with the study of the structure of rocks on the earth’s surface (Crust Layer).


Paleontology is the study of the fossils of ancient life forms and their evolution.

Historical Geology:

This is a combined study of stratigraphy and paleography. We will learn about the land, the seas, the climate of the old times.

Economic Geology:

It deals with fossils, fuels, minerals, and ores that are of great economic importance.

Mining Geology:

This is a study of the application of geology to mining engineering.

Other Important Branches of Geology

  • Oceanography
  • Geochemistry
  • Crystallography
  • Hydrology
  • Geophysical Exploration
  • Tectonic etc.

Mineralogy and Crystallography

Concepts of Point Group, Space, Reciprocal Lattice

Point Group:

  • In crystallography, the point group, also known as the crystal class, can list the orientation of the crystal without changing its position.
  • These orientation changes should include bus point activity of rotation about an axis, reflection in a plane, reversal about a center, or gradual rotation and reverse.
  • Only 32 individual combinations of these point activities are possible, as demonstrated by Johann FC, a German miner, as Hessel in 1830.
  • Each possible combination is called a point group or crystal class.
image 129


Space Group:

  • In the crystallography space group, the position of a crystal can change in any way without changing the position of its atom.
  • These changes may include the displacement of the crystal graphic axis (translation) as well as the entire structure as well as the activity of a point group of rotation about an axis, the reflection of a plane, the development of a center, or the gradual development of a sequence.
  • As shown in the 1890s, only 230 individual combinations of these changes were possible,
  • This 230 combination specifies 230 place groups. X-ray crystallography provides a specific method for classifying the internal symmetry of crystals by simply using X-ray crystals, and crystals can be assigned to one of these groups.
image 137


image 141


Fig. 4: Space-group-symmetry

Elements Of Space Group

The three-dimensional space clusters consist of groups of 32 crystal points with 14 Bravis synapses, each consisting of a successive la lattice system. This means that the action of any element in a given space group can be expressed as an action of an element at appropriate points by alternately following the translation. The space group is the point group refraction activity, rotation, and improper rotation (also called rotational inversion) of the unit cell (translation rigging centrally (with explanation) and some combinations between the helix axis and the slip plane alignment process. The combination of all these identical activities results in a total of 230 different space groups describing all possible crystal refractions.

Elements Fixing a Point:

  • The space group elements defining a point of space are the identity component, reflections, rotations, and inappropriate rotations.


  • Translations form a general subgroup of Rank 3 called Bravis lattice. There are 14 possible species of pride.
  • The Space Cluster Fragment by the Bravis Network is a finite array, which is one of 32 possible point combinations.

Glide planes:

  • A slip plane is a reflection in a plane followed by a translation parallel to that plane.
  • This is denoted by a, b, or c depending on which axis the slip passes through. There is also slip, which is sliding along a radius of the face, and sliding, which is a quarter of the way along a face or diagonal space of a unit cell.
  • The latter is called the diamond slip plane because it appears in the diamond structure. In 17 space groups, due to cell centering, sliders appear simultaneously in two vertical directions, i.e. The same sliding plane can be called b, c, a, b, a, or c. For example, the group Abm2 can also be called Acm2, and the group Ccca can be called Cccb. In 1992, it was used the symbol “e” for such aircraft.

Reciprocal Lattice:

  • The term “Reciprocal Lattice” has crept several times into the discussion. This falls naturally out of the Diffraction Theory as representations of the rules for when diffraction occurs in the cases of one-, two- and three-dimensional crystals.
  • Many crystallography designers use the concept of a reciprocating lattice as a way to visualize the many diffraction possibilities available when a single crystal is redirected or rotated.
  • Although diffraction can still be understood without the concept of reciprocal network, it is in widespread use and thus some general observations should be made.
image 145


Fig. 5: Reciprocal fcc lattice corresponds to a real bcc structure

Leave a Comment

Discover more from

Subscribe now to keep reading and get access to the full archive.

Continue reading