Proceedings of the United States National Museum . Ordinary light. Magnified 13 diameters. Lower: An albitic pegmatite devoid of quartz and micropegmatite. The clearmineral is colorless diopside and the gray is kaolinized albite. The large irreg-ular dark areas in the section are skeleton magnetites largely replaced by titan-ite and filled with chlorite. Ordinary Hght. Magnified 13 diameters. Plate 8. Albitic pegmatite grading into diabase pegmatite. Shows long blades of dial-lagic augite. At the lower end of the specimen the groundmass is largely pla-gioclase but the feldspar of the balance i
Proceedings of the United States National Museum . Ordinary light. Magnified 13 diameters. Lower: An albitic pegmatite devoid of quartz and micropegmatite. The clearmineral is colorless diopside and the gray is kaolinized albite. The large irreg-ular dark areas in the section are skeleton magnetites largely replaced by titan-ite and filled with chlorite. Ordinary Hght. Magnified 13 diameters. Plate 8. Albitic pegmatite grading into diabase pegmatite. Shows long blades of dial-lagic augite. At the lower end of the specimen the groundmass is largely pla-gioclase but the feldspar of the balance is albite. The long pyroxene blades arereplaced along their borders and at the tips by diopside. -y^ natural size. Plate 9. Upper: Micropegmatite in patches growing out from the wall (left) towardthe granular center of the analyzed aplite dike. Ordinary light. Magnified 13diameters. Lower: Albitic pegmatite from waU of the mass illustrated in Plate 6. Ordi-nary light. Magnified 13 diameters. o U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 66, ART. 2 Diabase Pegmatite in Diabase For EXPLANATrON OF PLATE SEE PAGE 85 U. S. NATIONAL MUSEUM PROCEEDINGS, VOL. 66, ART. 2 PL. 2
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
