Fort Settlement map 5440 Elkins Road Sugar Land, TX 77479 (281) 634-6440. Garcia map 18550 Old Richmond Rd. Sugar Land, TX 77498 (281) 634-3160. Hodges Bend map 16510 Bissonnet Houston, TX 77083 (281) 634-3000. Lake Olympia map 3100 Lake Olympia Parkway Missouri City, TX 77459 (281) 634-3520. McAuliffe map 16650 South Post Oak Houston, TX 77053 (281) 634-3360. Missouri City map
Within the feldspar group, the plagioclase minerals are only differentiated from the potassium feldspars by the presence of parallel striations seen on some plagioclase cleavage surfaces. Potassium Feldspar:
7A). The garnet-plagioclase rims formed under lower pressures, but over a large pressure-range (3.5-5.5 kbar at 700 C). A similar pressure range is also obtained by using the garnet-plagioclase-biotite-quartz (GPBQ) barometer of Hoisch (1990). Pressure estimates using the GASP geobarometer for garnet I rims should be considered as maximum values, because of the lack of an Al-silicate in equilibrium with assemblage 1.