Book Notes-Optical Mineralogy

Book Notes-Optical Mineralogy -...

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Use optic axis interference figure to Introduction Grain mounts o Crushed mineral sample with immersion oil under coverslip to  surround grains Thin section o Thin slices of rock or mineral mounted on slide; .03mm; cemented  coverslip Light When electrons move down to normal energy level energy released  as light Light Waves o Electromagnetic radiation- both electrical and magnetic properties o Visible light Consist of elec and mag vectors vibrating at right  angles to direction which energy is propagating o V- nm/sec, wavelength- nm, frequency- cycles/ sec or Hz o Wave front- surface that connects same pts on adjacent  wavelengths o Wave normal- line drawn at 90 deg to wave front and represents  direction wave could move o Light ray- propagation direction of light energy, = to path followed by  photon o Polarized Light o Plane polarized- if vibration of light lies in single plane o Polarizing film- piece of anisotropic plastic; splits unpolarized light  into 2 plane polarized rays at 90 deg; one ray completely absorbed  other only partially and passes through Interaction of Light and Matter Dependent on material and wavelength of light
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Max- 3.0 x 10^17 nm/sec Frequency constant when going from mineral to other mineral Optically Isotropic v. Anisotropic Materials o Isotropic Velocity of light same in all directions Volcanic glass and isometric crystal system Electron density same in all directions -> electron field same in  all directions o Anisotropic Velocity of light different in all directions Tetragonal, hexagonal, orthorhombic, monoclinic, triclinic  systems Lower symmetry-> electron density varies w/ direction Reflection and Refraction o Reflected- angle of incidence and refraction are = o Angle of incidence increases so does amount of light reflected at  surface o Index of refraction (n)- measure of how much light will be bent     n  = Vv/Vm o Snell’s Law- angle that light is bent passing b/w materials    sin  (theat1)/ sin (theta2) = n2/n1 o Light passing from low index to high can refract b/c angle of refract  > angle of incidence o Light from high to low can’t pass boundary if angle of incidence >  critical angle (CA) o CA- angle of incidence that gets angle of refract at 90 deg n1 (low) / n2 (high) = sin CA o Total internal reflection- angle of incidence > CA
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Dispersion  o Normal dispersion of refractive indexes- index of refract is higher for  short wavelengths and lower for long wavelengths o Fraunhofer Lines- absorption line’s in sun’s spectrum o
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This note was uploaded on 09/26/2010 for the course GEO 416k taught by Professor Staff during the Fall '08 term at University of Texas.

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Book Notes-Optical Mineralogy -...

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