Brauns, R. (Reinhard), 1861-1937, Spencer, Leonard James, 1870- · Esslingen a. N. : J. F. Schreiber · leaf 305
ROCKS AND ROCK-FORMING MINERALS. 280 time a lens (called a Bertrand lens) in about the middle position in the tube of the instrument. On some of the preceding pages of this volume we have had occasion to call the microscope to our aid to exhibit certain structures and pecularities which are not… … of pressure or temperature, or that the com- Fig. 211. Flow structure shown in a thin section of lava. position of the liquid, have varied during Magnification 45. the period that the rock was formed. Fur- ther, the structure of the rock itself is often much more obvious under the microscope than…
Mineralogy
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