Figure F19. Microcrystalline variolitic and coarser grained patches coexisting in the groundmass of the interior of the massive basal part of Unit 6 in Sample 192-1187A-12R-5 (Piece 2A, 90-93 cm). In hand specimen, the rock has a mottled appearance (field of view = 2.5 mm; plane-polarized light; photomicrograph ID# 1187A_255).