. Bulletin - New York State Museum. Science. 338 NEW YORK STATE MUSEUM rock upon the observer and this is due to the abundance of magnetite grains and dark silicates. The minerals present are plagioclase, green monoclinic augite, brown hornblende, hypersthene, garnet, titaniferous magnetite and titanite. The more important ones of these are shown in the accompanying figure (Fig. 2) which is a little. Fig. 2.—Gabbro without reaction rims — near Ensign Pond, Moriah. F is labradorite; P, augite; Hy, hypersthene; H, hornblende; Q, quartz; G, garnet; M, magnetite. richer in hornblende than the aver
. Bulletin - New York State Museum. Science. 338 NEW YORK STATE MUSEUM rock upon the observer and this is due to the abundance of magnetite grains and dark silicates. The minerals present are plagioclase, green monoclinic augite, brown hornblende, hypersthene, garnet, titaniferous magnetite and titanite. The more important ones of these are shown in the accompanying figure (Fig. 2) which is a little. Fig. 2.—Gabbro without reaction rims — near Ensign Pond, Moriah. F is labradorite; P, augite; Hy, hypersthene; H, hornblende; Q, quartz; G, garnet; M, magnetite. richer in hornblende than the average. The rock is blotched with light green from the altered feldspar, and has faint, pink streaks running through it, due to the garnets. These latter give it a pecu- liar reddish cast that is very characteristic. The feldspars are now largely altered to saussuritic matter, but when not too far gone they have a broad, lath-shaped outline, more or less idiomorphic, and are rather coarsely twinned. At times they are filled with minute dots or crystals of brightly polarizing character which are so small as not to be easily recognized, but they are probably pyroxene. Less commonly, polygonal scales of a brown color and in geometrical arrangement are to be seen. These latter are generally regarded when seen in other exposures as a micaceous variety of ilmenite. The successive zones of grains of garnet and brown hornblende between the dark silicates and the feldspar, or surrounding the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York State Museum; New York State Museum. Albany : New York State Education Dept
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1887
