The geology of Ascutney Mountain, Vermont . cised bj^ the country rock on the eruptive. Basic nodules, from 1 to 2 inches (2.(3 to centimeters) in diameterare occasionally seen in the quarry rock. They are differentiated min-eralogically from their parent rock simply by a greater richness inhornblende, which is here, too, strikingly corroded. One can not besure that the poikilitic habit of the mineral is anything more thanapparent; primarj^ inclusion of quartz and feldspar might give thesame appearance in thin section as that due to extensive embaying ofthe hornblende by the caustic feldsp
The geology of Ascutney Mountain, Vermont . cised bj^ the country rock on the eruptive. Basic nodules, from 1 to 2 inches (2.(3 to centimeters) in diameterare occasionally seen in the quarry rock. They are differentiated min-eralogically from their parent rock simply by a greater richness inhornblende, which is here, too, strikingly corroded. One can not besure that the poikilitic habit of the mineral is anything more thanapparent; primarj^ inclusion of quartz and feldspar might give thesame appearance in thin section as that due to extensive embaying ofthe hornblende by the caustic feldspathic magma. PLATE IV. A. Typical thin section of the nordmarkite of the Main stock, granitic phase,composed ahnost entirely of microperthite and qixartz; crossed nicols, X 30. (Seep. 50.) B. Pyroclastic feldspar (soda-orthoclase) surrounded by a reaction rim rich inalkaline hornblende, from the large paisanite dike on northwest slope of AscutneyMountain; crossed nicols, X 7. (See p. 71.) 58 U. S. GEOLOGICAL SURVEY BULLETIN NO. 209, PL. IV. (B) HE MERIDEN GRAVURE CO. DALY.] MAIN SYENITE STOCK. Table YII.—Analyses of nordmarkite and other rocks. 59 1. 2. 3. 4. 5. j 1 a 0. 59 6. 7. 8. SiOa -- , i [ 3. 80 U. 0- « ( 1 0 22 Fe-A FeO MgO- CaO 1 36 Na,0 5 95 K^O- H.,0 above 110° C. HjO below 110° C_-COo None. TiOa 1 ZrO^ P2O, SO3 CI F FeSa BaO Faint trace. Trace. None. MnO Trace. SrO LijO Stronsr trace. 0—F CI Totals - a Loss
Size: 1081px × 2310px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherwashi, bookyear1903
