. Bulletin of the Geological Society of America. Geology. Figure 3.—Photomicrograph of Quartz-mica Schist icith SilUmanite. X Nicols. (X 20) Locality, 1% miles northeast of Mountainville, Allentown quadrangle. Specimen 7323. The sillimanite shows mesh-structure owing to alteration to pinite along transverse cracks ; the bulk of the field is occupied by sericite, with a few irregular grains of quartz. Figure 4.—Photomicrograph of Quartz-mica Schist tvith Garnet. Ordinary Light. (X 20) Locality, 1 mile north of Springtown, Allentown quadrangle. Specimen 253. The bulk of the field is occupied by
. Bulletin of the Geological Society of America. Geology. Figure 3.—Photomicrograph of Quartz-mica Schist icith SilUmanite. X Nicols. (X 20) Locality, 1% miles northeast of Mountainville, Allentown quadrangle. Specimen 7323. The sillimanite shows mesh-structure owing to alteration to pinite along transverse cracks ; the bulk of the field is occupied by sericite, with a few irregular grains of quartz. Figure 4.—Photomicrograph of Quartz-mica Schist tvith Garnet. Ordinary Light. (X 20) Locality, 1 mile north of Springtown, Allentown quadrangle. Specimen 253. The bulk of the field is occupied by garnet; it contains numerous inclusions of clear quartz and a few mottled gray patches of micaceous material. Figure 5.—Photomicrograph of Quartz-mica Schist shoicing rounded Zircons. Ordinary Light. (X 100) Locality, east edge of Allentown quadrangle. Specimen G396. The clear pale gray areas are quartz ; the Y-shaped mass in the center is sericite ; round zircons of all sizes standing out in relief are to be seen around the right-hand arm of the Y. Figure 6.—Photomicrograph of Oranite, shoioing angular Zircons, for Comparison. Ordinary Light. (X 100) Locality, ridge southeast of Lower Saucon, Allentown (juadrangle. Specimen GSGO. Two attached zircon crystals api)ear near the center; they show distinct angular 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 Geological Society of America. [New York : The Society]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
