Figure 39. Bivins Ranch No. 4-3, 5213.2 feet in central part of porous shaly sandstone. Core porosity = 14.1%; permeability_(air) = 4.2 md. Good primary porosity between framework grains of monocrystalline quartz, feldspar, and other constituents. Rock is lithic arkose to feldspathic litharenite. Pseudomatrix in upper left (brown patch) is a result of compaction and alteration of argillaceous sedimentary rock fragment.