Proceedings of the United States National Museum . lbite, diopside, chalcopy-rite, byssolitic hornblende, epidote,and chlorite. Moreover, the reac-tions of these solutions on the adja-cent pegmatites produced, in thefirst stage, diopside from augite,albite from plagioclase, and titaniteby the replacement of magnetite. Ata later stage the diopside was re-placed by fibrous hornblende. In the most common type ofhydrothermal alteration along thediopsidizing seams, the reactions ofthe solutions upon the previouslyconsolidated normal diabase formingthe walls of the crack are the same,namely, albitiz
Proceedings of the United States National Museum . lbite, diopside, chalcopy-rite, byssolitic hornblende, epidote,and chlorite. Moreover, the reac-tions of these solutions on the adja-cent pegmatites produced, in thefirst stage, diopside from augite,albite from plagioclase, and titaniteby the replacement of magnetite. Ata later stage the diopside was re-placed by fibrous hornblende. In the most common type ofhydrothermal alteration along thediopsidizing seams, the reactions ofthe solutions upon the previouslyconsolidated normal diabase formingthe walls of the crack are the same,namely, albitization of the plagio-clase, followed by sericitization,diopsidization of the augite and replacement of the magnetite bytitanite. In the open space of the central crack the minerals de-posited were diopside with less chlorite and titanite and, rarely,axinite. No definite line can be drawn separating the thin seams accom-panied by hydrothermal alteration, from the miarolitic cavities onthe one hand and from the zeolite bearmg veins on the other. The. Fig. 31.—Calcite showing the common-est HABIT OF AMBER COLORED CALCITEOCCURRING IN THE VEINS. 84 PROCEEDINGS OF THE NATTONAX, MUSEUM. VOL. 66.
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
