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Title: Statistical method in optical crystallography: technique and application to rock forming minerals 
Author: Langford, Stephen A.
Date: 1972
Publisher: [Honolulu]
Abstract: This work provides a new rapid way to determine mean principal refractive indices of minerals. Crushed mineral grains yield immersion data which are treated in a way new to optical crystallography. The mineral families so treated yield mean refractive indices and the standard deviation of the refractive index probability .function .for each sample. Raw data are provided by the percent of randomly encountered mineral grains which display indices less than, equal to, and greater than each of several different immersion medium re1ractive indices. The mean refractive indices from randomly encountered grains are plotted against the mean indices for grains of the same sample population oriented in chosen principal optical directions. Statistics are treated graphically with probability paper or with electronic computer programmed to simulate normal probability paper. Plagloclase feldspars, olivines, augitic clinopyroxenes and orthopyroxenes are treated. A third degree equation is fit to 26 data points for plagloclases. The other mineral families yield straight line equations. However the data for olivines and pyroxenes are considered preliminary, being based on fewer data points than were obtained :for p14gioclases, and only Linear fits were completed. A temperature-controlled modified Jelley refractometer capable of measuring oil refractive indices to accuracies of 0.001 and precisions of 0.0002 is coupled to and calibrated with a temperature-controlled microscope stage. The costs in time and money of this method are Less than for conventional optical methods. The portability of the system make it applicable to use in the 1ield or aboard ships. The precision and flexibility of the system permit the empirical drafting of density 1unctions 10r specimens which do not display a Gaussian distribution o£ indices. A 1eaa1bility study is made of the applicability of the technique to derivation of rock modes.
Description: Typescript. Thesis (Ph. D.)--University of Hawaii at Manoa, 1972. Bibliography: leaves 131-138. 185 l illus., tables
Rights: All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Keywords: Crystal optics, Mineralogy, Rocks, Mineralogy -- Hawaii

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