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This text describes the theory and practice of optical mineralogy in terms useful to all practitioners from the beginning student to the professional in field and laboratory geology and industrial and environmental mineralogy. The author's aim is to provide the simplest possible access to the most powerful techniques of optical crystal identification. The book emphasizes useful practical theoretical material and methods for studying both thin sections of rocks and immersion of mineral grains in refractive index liquids. It contains original research results found in no other text. A major goal of the text is to allow precise determination of refractive index and the essential composition of crystals belonging to important mineral groups such as olivine, feldspar, and pyroxene. New methods for achieving this are developed for both white light and colored light of variable wavelength. Among the book's unique features is the color fringe chart developed by Prof. Morse for estimating both the direction and degree of mismatch between the refraction index of a crystal and that of the surrounding liquid medium in the immersion method. Further, a new algebraic treatment of the dispersion method allows a high precision of match between crystal and liquid. An original classification of interference figures aids crystal identification. Worked examples of refractive index determination and crystal identification are given for each optical class of crystals. The optic orientation of optically biaxial crystals is illustrated with examples from each crystal system portrayed in stereographic projection. Principles and applications of crystal identification with the dispersion method are developed in a separate chapter. The final chapter is a practical, step-by-step guide to crystal identification in thin section or immersion. An identification table for the most common asbestos minerals, including the dispersion staining method used by most environmental laboratories.
Simple text and photographs describe and illustrate how to use a microscope.
Outside the laboratory windows was a watery-grey fog, and within a close warmth and the yellow light of the green-shaded gas lamps that stood two to each table down its narrow length. On each table stood a couple of glass jars containing the mangled vestiges of the crayfish, mussels, frogs, and guinea-pigs upon which the students had been working, and down the side of the room, facing the windows, were shelves bearing bleached dissections in spirits, surmounted by a row of beautifully executed anatomical drawings in white-wood frames and overhanging a row of cubical lockers. All the doors of the laboratory were panelled with blackboard, and on these were the half-erased diagrams of the previous day's work. The laboratory was empty, save for the demonstrator, who sat near the preparation-room door, and silent, save for a low, continuous murmur and the clicking of the rocker microtome at which he was working. But scattered about the room were traces of numerous students: hand-bags, polished boxes of instruments, in one place a large drawing covered by newspaper, and in another a prettily bound copy of News from Nowhere, a book oddly at variance with its surroundings. These things had been put down hastily as the students had arrived and hurried at once to secure their seats in the adjacent lecture theatre.
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