| When the sandstone contains appreciable quantities of feldspar the rock is called arkose. |
| Quartz is associated most commonly with aegirine and potassium feldspar as well as zircon. |
| These granite dikes are composed almost totally of potassium feldspar and quartz. |
| The siltstones are composed of angular quartz and rare feldspar, set in a finer matrix that locally contains some calcite. |
| The plagioclase feldspar weathers to produce a whitish gray rock, while the mafic minerals produce contrasting darker grains. |
| A plagioclase feldspar, albite probably, occurs as parallel growths of transparent colorless to yellowish crystals. |
