. Transactions. Fig. 5. Fig. 6. Fig. 5.—Quartz porphyry showing crushed quartz and feldspar pheno-crysts and fine-grained groundmass. crossed nicols. x 30. Fig. 6.—Quartz porphyry showing fractured feldspar phenocrysts veinedwith carbonate. Crossed NICOLS. X Fig. 7.—Quartz porphyry, showing pyrite cubes (black) in veinlet cuttingrock. Ordinary light. X 30. be expected of a series of small intrusions, are somewhat variable incomposition and habit. They also show different amounts of dynamicdisturbance Some show no trace of fracturing, while others have quartz,chlorite, and carbonate veins
. Transactions. Fig. 5. Fig. 6. Fig. 5.—Quartz porphyry showing crushed quartz and feldspar pheno-crysts and fine-grained groundmass. crossed nicols. x 30. Fig. 6.—Quartz porphyry showing fractured feldspar phenocrysts veinedwith carbonate. Crossed NICOLS. X Fig. 7.—Quartz porphyry, showing pyrite cubes (black) in veinlet cuttingrock. Ordinary light. X 30. be expected of a series of small intrusions, are somewhat variable incomposition and habit. They also show different amounts of dynamicdisturbance Some show no trace of fracturing, while others have quartz,chlorite, and carbonate veins and crush effects in the phenocrysts. Mostof the specimens contain pyrite in the veins (Fig. 7); some as perfectcubes and some as crushed fragments. Black rims on the pyrite resultfrom secondary processes. 04 PETROGRAPHIC NOTES ON THE ORE DEPOSITS OF JEROME, ARIZ. The quartz porphyries, then, were intruded during the closing stages;of the regional disturbance, and also after movement had stopped. Themineralization follows fractures in the porphyry and therefore is laterin each case than the rock in which it is found, but is not necessarilylater than the entire porphyry series, so that ore may be found cuttingthe dikes, and likewise dikes cutting the ore
Size: 1450px × 1723px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
