Mineral chemistry. — A, example of Clefcy vaugnerite microchemical map: mineral abbreviations following Whitney and Evans (2010). Yellow ovals locate feldspar areal-analyses through SEM-EDS. Note the variegated core (Pl ± Kfs ± sericite) due to subsolidus unmixing, the more uniform rim (oligoclase), and the euhedral biotite (Bt) laths enclosing most of the apatite crystals (Ap). — B, Al-Fe + Mn-Mg (at.) triangle with biotite SEM-EDS point-analyses for: 1, the Vo14-16, dated granite-gneiss; 2, various vaugnerites. — C, triangle Ab-Or-An (mol.), using same symbols as B for point analyses, plus areal-analyses of vaugnerite plagioclase crystals (including the ovals in A) plotted as empty circles to the right of the black line.