This granite is the marginal facies (chill zone?) of the Katemcy Pluton and has an appearance unlike any other granite I've seen from the Llano Uplift. The texture is dominated by large pink microcline crystals with visible perthitic texture. In the upper central portion of the photo there are a number of dark-looking crystals in the matrix (one of them has an inverted teardrop shape). Though they photographed dark, they are quartz phenocrysts with generally euhedral shapes. I suspect this is an example of quartz preserving it's original Beta-quartz crystal shapes.
The Katemcy Pluton is the youngest (1070 Ma) pluton yet dated in the Llano Uplift. This would be a possible explanation for why this pluton seems to have a chill zone and other plutons in the Uplift do not.

For those of you acquainted with Llano geology, this is sample M-4 from Barnes, V.E. , Dawson, R.F., and Parkison, G.A. (1947) Building Stones of Central Texas. University of Texas Publication no. 4246, 198 pgs