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:
Orthoclase is a common constituent of most granites and other felsic igneous rocks and often forms huge crystals and masses in pegmatite. Typically, the pure potassium endmember of orthoclase forms a solid solution with albite, the sodium endmember (NaAlSi 3 O 8), of plagioclase.he name is from the Greek for straight fracture, because its two cleavage planes are at right angles to each other. It is a type of potassium feldspar, also known as K-feldspar. The gem known as moonstone (see below) is largely composed of orthoclase.