Introduction covering the following topics:
Course identity and main aims of its study.
The importance of course for economic geologists.
Subdivisions of the course.
A refreshing account on the main aspects of optical mineralogy.
The components of ore microscope; the mechanism of working of ore microscope
The main differences between the optical properties of minerals in both transmitted and reflected lights.
The main objective of the course is supplying students with the different aspects of the light behavior on polished surfaces.
The students are supposed to be informed with a collective idea about the intimate relationship between ore microscopy and the branch of ore dressing since the interlocking index of ore and gangue minerals strongly determines the proper method of ore beneficiation.
The course also demonstrates the main groups of ore minerals under the ore microscope.
As an output, the course is intended to give students expertise in handling the problems connected to ore genesis and beneficiation. Accordingly, the students would be able to use the materials of the course in their future career, especially for those who will work in the mining companies and authorities, as well as the concentration plants.
Mid-Terms Exams (3 or 4 Exams) 40%
Students Activities (including subjects in mineralogy and mineral paragenesis of some ore deposits) 10%
Final Practical Exam 30%
Final Theoretical sheet 20%
Preparation of different kinds of polished surfaces (sections and slabs).
This account will demonstrate the precautions to be considered during the preparation of the polished surfaces.
The account also covers the aspect of how to overcome the imperfections to in order to ensure good quality surfaces.
Optical properties of ore minerals in ordinary light (without using the polarizer and analyzer).
These properties include form, habit, fractures, hardness and zoning.
Optical properties of ore minerals in polarized light (using the polarizer only, and analyzer out).
They include color, reflection pleochroism and reflectivity
Optical properties of ore minerals between crossed-nicols (using both the polarizer and analyzer). They include anisotropism, internal reflection and twinning.
The group of native elements.
The group of sulphide minerals.
The group of oxide minerals.
Ore Textures: Descriptive and genetic classifications of ore textures.
1. Descriptive ore textures:
Single Grains
1. 1. 1. Internal
· Zoning
· Twining
1. 1. 2. External
· Morphology
Xenomorphic (= Allotromorphic Textur)
Hypidiomorphic Texture
Idiomorphic (= Panidiomorphic ) Texture.
· Grain-size
· Grain and crystal relationship
Simple banding
Complex banding
Space filling
Crustified banding
Comb or cockad texture
· Nucleation
· Intergrowths
Emulsion intergrowth
Myrmeckitic texture
Oriented intergrowth
Penetration intergrowth
Aggregates
1.2.1.Arrangement aggregates
· Breccia aggregates
· Oriented, lineated or fibrous aggregates
· Rundum aggregates
· Rhythmic textures
1.2.2. Contact and intergranular rims and films
1.2.3. Inclusions
Genetic classification of ore textures:
Primary ore textures
Primary growth Texture
Colloform Textures:
botryoidal texture
Concentrically banded texture
Reticulate texture
Spherical Texture
Granular textures:
Salt and Pepper structure
Graphic and subgraphic textures
Zonal texture
Primary Depositional Textures
Oolitic texture
Theories of formation of oolitic textures
Spheroidal textures
Primary growth ore textures: Growth zoning and colloform textures.
Primary depositional Textures: Banding and laminations, vertical grain size variations and oolitic textures.
Secondary textures:
Secondary replacement textures: rim, zonal, atoll, carrier, selective and irregular types.
Secondary deformational textures.
Paragenesis of ore minerals: tools used in determining the paragenetic sequence. i. e. crystal shape, concavity and convexity of crystals, colloform textures, replacement textures, cross-cutting relations, etc…...
The application of ore microscopy in ore dressing, upgrading and beneficiation.
Ore microscopy of representative examples of some mineral deposits from Saudi Arabia.
4