Lecture Notes - Powder Diffraction
X-ray diffraction by mineral powders is one of the mineral identification and
characteriziation techniques most used by geologists. Powder diffraction experiments require only a small quantity of a mineral. As little as
Lecture Notes - Mineralogy - Plane Patterns
Back in September we observed the constancy of interfacial angles in all crystals of the same
mineral. Based on this observation we concluded that minerals are built according to a pattern.
We identified vector
Lecture Notes - Optics 7: Biaxial Minerals
The interference figure obtained for a biaxial mineral depends on the orientation of the mineral
with respect to the microscope stage. Four types of interference figure are commonly considered:
(a) BxA figure -
Lecture Notes - Optics 6: Measurement of n and n, Spindle Stage
The variation of the velocity of light with vibration direction in uniaxial minerals can be fully
characterized by determining just two refractive indices, n and n. These two indices may be
Lecture Notes - Optics 5: Uniaxial Minerals, Interfences Figures, Indicatrix
Tetragonal and hexagonal crystals all have one unique rotation axis, the c-axis, which is a 4fold,4, 6-fold, or6, 3-fold,3 axis. Measurements of refractive indices for tetragona
Lecture Notes - Optics 4: Retardation, Interference Colors
In anisotropic crystals, the two rays of light produced by double refraction travel at different
velocities through the crystal. It takes the slow ray longer to traverse the crystal than it takes
Lecture Notes - Optics 3: Double Refraction, Polarized Light
Experiment: observations with optical calcite.
Light passing through a calcite crystal is split into two rays. This process, first reported by
Erasmus Bartholinus in 1669, is called double ref
Lecture Notes - Optics 2: Becke Lines, Dispersion
The refractive index of a cubic (system) crystal or a homogeneous non-crystalline material (such
as glass or a fluid) does not vary with the direction of light propagation. Therefore, these
Lecture Notes - Optics 1: Electromagnetic Waves, Snell's Law
We now embark on a four-week digression to consider the physics of the interaction of light
with non-opaque minerals. Application of these principles through the use of a polarizing microscope
Lecture Notes - Mineralogy - Miller Indices
All directions and planes in a mineral are referenced to a crystallographic coordinate system.
This is always a right-handed coordinate system based on the unit cell of the mineral.
Rational directions in a mine
Biaxial Minerals: The Spindle Stage and EXCALIBR II
The following is a recipe for determining the three principle refractive indices of a biaxial mineral
(n, n, n) using a detent spindle stage and the computer program EXCALIBR II.
I. Aligning the spindle
Lecture Notes - Mineralogy - Diffraction
Two of the most fundamental aspects of a mineral, its space group and unit cell,
can be determined from x-ray diffraction experiments. To understand these experiments, which we will do in lab, we
Lecture Notes - Mineralogy - Crystals are Patterns
A mineral is a naturally occurring, inorganic
Interfacial angles for good mineral crystals are
measured perpendicular to the line of intersection
of two crystal faces. The angle reported is alway
Lecture Notes - Mineralogy - Crystal Classes
All patterns, including minerals, may be grouped according to the symmetry that they possess.
Symmetry is defined as "invariance to an operation." The operations involved (rotation,
reflection, translation, an