Figure F56. Photomicrographs of alteration of gabbroic rocks. A, B. Sample 335-1256D-Run11-EXJB-J4 (Thin Section 12): (A) Clinopyroxene replaced by amphibole + trace magnetite (plane-polarized light). Plagioclase is partly altered to secondary plagioclase along numerous fractures. Fe-Ti oxide (black) is highly altered to titanite at right. (B) Coronitic alteration of olivine (cross-polarized light). Olivine rim is altered to magnetite (black) and amphibole + talc. Veinlets of magnetite + talc cut the olivine. C. Plagioclase (gray) highly altered to secondary plagioclase + amphibole (Sample 335-1256D-Run12-RCJB-Rock B; Thin Section 21) (cross-polarized light). Clinopyroxene partly altered to amphibole + magnetite and interstitial areas altered and filled with amphibole.
Previous | Close | Next | Top of page