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Crystalography & Mineralogy (ERSC 3001)

Course Contents

Course Title : Crystallography & Mineralogy
Course Number: ERSCI 3001
Credit Hours: 3 ( 2 Theoretical, 1 Practical)
Prequesites: General Geology Geo101

Instructor: Prof. Dr. Sobhi Nasir

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Objectives:

The aim of this course is to study the external semmetry of the crystals through external elements of symmetry, crystal classes and systems, and the relations of symmetry to the internal structure using the chemical and physical properties of the minerals. The course aims also to study the major mineral groups, their occurrences, physcial, chemical and crystallographic properties and their possible uses in industry.

Text Book:

Manual of Mineralogy (1993), 21th ed. Klein C. & Hurlbut, H. Wiley:

Laboratory and homework assignments: Excercises in Crystasllography, Mineralogy and hand specimen petrology. (1993) Klein, C. Wiley Pub.

References

An introdcution to Crystallography. (1980), 4th Ed. Phillips, F.C.

Rock forming Minerals (1985): Deer, Howie, R., and Zussman, J.

Educational Facilities:
1- Transparency and slides
2- Computer: Minkey, shape,Minpet, Rockware, Ferric, Minfile, Formula
3- Video Films:Crystals and X-ray, Crystals, Mineral's structure, Silicate
4-- Group teaching and lecturing by the students.
Evaluation Strategy:
1- Term Activities: 45 % of the Total and includes:10% Quizzes , 10% Activities, 25% Laboratory
2- Mid-Term Examination: 20 % of the Total
3- Fina Examination: 35 % of the Total

Coarse Contents:

Part One: Morphology of Crystals
1- Introduction: ( 4 lectures)
Definition: Mineral, Crystal, Crystalline substances, Crystallization, Crystal growth, Crystal habit, Concept and methods of crystal growth, Morphology, Symmetry elements, Law of symmetry, Axial ratios and paramters, Indices of faces, Crystal forms
2- Crystal Projectuions, (sterogram, sterographic, clinographic and spherical projections), Zones ( 2 lectures)
3- Crystal Systems and Classes ( 2 lectures)
4-The 32-Crystal Classes ( 2 lectures)

Part II: Crystal Structure-Chemistry and Physical Properties
1-Space groups and Crystal Structure (2 lectures)
2-X-Ray
3-Crystal Chemistry
4-Physical Properties

Part III: Systematic Mineralogy and Classifications (14 lectures)
Non-silicates: Native elements, Sulfides, Sulfosalts, Oxides, Hydroxides, Halides, Carbonates, Sulfates, Phosphates, Vanadates, Tungestates
Silicates: Neso-silictaes, Sorosilicates, Cyrclo-silicates, Chain-silictaes, Phyllo-silicates, Tecto-silicates

Introduction

Mineralogy

Mineralogy is defined as the study of minerals, their properties, occurrences, genesis and their classification

Mineral:

A mineral is deined as a naturally-occurring, homogeneous solid having an ordered internal atomic structure and a definite, but generally not fixed, inorganic chemical composition and an ordered atomic arrangement.

Synthetic compounds are not minerals. Rocks are aggregates of minerals. They are not homogeneous as they contain more than one compound in different directions. Liquids and gases are not minerals. Disordered solids like glasses are also not minerals.

Crystallography

Crystallography is defined as the study of crystals and their structural properties

Some Characteristics of crystals:

Faces: Surfaces that bounded the crystal. The number of faces in a crystal is a diagnostic character. Faces are of two kinds; like and unlike.

Forms: Faces which have common elements of symmetry are called form. A crystal made up of like faces is termed simple form. Combined form is characterized by tow or more simple forms. They canít enclose space by themselves and called open forms. Simple forms can enclose space by themselves and considered as closed forms.

Edge: An edge is formed by the intersection of any two adjacent faces.

Solid angel: This the angel formed by the intersection of three or more faces.

Interfacial angel: The angel between any two faces of a crystal. It is formed by the intersection of two normal lines taken along two adjacent faces.

Law of constancy of interfacial angle The interfacial angles are constant for all crystals if a given mineral with identical composition at the same temperature. Interfacial angles are measured by a contact goniometer.

Crystallographic Axis

Crystallographic axis are imagenary lines taken parallel to the major faces in the crystal. The position of a plane in space is given by the interceptd (the lengths cut off) that the plane makes on three given lines called the axis. The crystallographic axes intersect at the origin.

All crystals, with the exception of those belonging to the hexagonal system, are referred to three crystallographic axes designated as : a, b, and c. Hexagonal and trigonall crystals are refered to four axis. The angle between a and c is called b and beween b and c is called a and between a and b is called a. The six crystal systems are rferred to the following axial angles:

Triclinic: three unequal axis all interescting at oblique angles

Monoclinic: Three unequal axes, two of which are inlcined to each other (a and b, angle b) and the third perpendicular to the plane of the other two.

Orthorhombic: Three mutually perpendicular axes all of different lengths.

Tetragonal: Three mutually perpendicular axes, the horizontal two axes are of equal length, but the vertical axis is shorter or longer than the other two. Major forms: Basal pinacoid, prism, bipyramid, ditetragonal prism, ditetragonal bipyramid.

Hexagonal (Trigonal and hexagonal divisions): refered to four axes, three equal horizontal axes interesect at angels of degrees, the fourth is verical and of different length and perpendicular to the plane of the other three.

Isometric: Thre mutually perpendicular axes of equal lengths. Major forms: Cube ( six faces), octahedron (eight faces), Rhombic dodecahedron ( faces), tetrahexahedron ( faces), trapezohedron ( faces), trisochtahedron ( faces), hexaoctahedron ( faces).

Types Crystal Forms

Pedion: A single face

Pincacoid: Two parallel faces

Dome: Two non-parallel faces with a symmetrical plane

Sphenoid: Tow non-parallel faces with a symmetrical axis

Disphenoid: Tow upper sphenoid faces alternate with two lower sphenoid faces.

Prism: 3, 4, 6, 8 or 12 faces all parallel to same axis

Pyramid: 3, 4, 6, 8 or 12 non-parallel faces that connected at a point.

Dipyramid: 6, 8, 12, 16 or 24 faces, half of them at the top and the other at the bottom. (two reflected pyramids)

Scalenohedron: 8 or 12 faced with faces grouped in symmetrical pairs. Each face is a scalene.

Trapezohedron: 6, 8 or 12 faced with 3, 4 or 6 faces above being offset from the faces below. Each face is a trapeze.

Rhombohedron: 6 faces, 3 at the top alternating with three faces at the bottom. Each face is a rhombohedra. The faces being offset by 60 degrees. I

Links to Mineralogy & Crystallography

Angelfire - Easiest Free Home Pages
Mineralogy at the University of Wiscanson
Links to Mineralogist at the University of Wuerzburg
Mineralogy Online
Mineralogy at the University of Idaho
Mineralogy at the Internet
Mineralogy course and links
Mineralogy at the University of Colorado
Links to Mineralogy world wide web
Mineralogy on the Web
Mineralogical Society of America
Mineralogical Education at EDU2

Email: sobhi@cheerful.com