Figure F46. An example of relatively uncommon plagioclase alteration in troctolite (Thin Section 72; Sample 345-U1415J-18R-1, 141–143 cm [Piece 17B]). A, B. Replacement of plagioclase by prehnite (Prh), chlorite (Chl), and very fine grained garnet (Grt). Clinopyroxene (Cpx) rim around plagioclase is partially replaced by chlorite. White box in B shows area of enlargement in C. Srp = serpentine, Ol = olivine. C. Plagioclase replacement by prehnite and chlorite showing seams of garnet. Chlorite replaces thin clinopyroxene rims. A is under plane-polarized light; B and C are under crossed polars.
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