Two generations of late plagioclase are seen in a specimen of quartz diorite about a mile north of Bruces Eddy. Clearwater County, Idaho. circa 1950.

Album caption: Two generations of late plagioclase are seen in a specimen of quartz diorite about a mile north of Bruces Eddy. The ealier plagioclase was crystallized as large grains in biotite quartzite and gneiss, the remnants of which are seen at left. The large white grains in the diorite are remnants of the same early plagioclase. The small grains of plagioclase in the quartz diorite are later. Clearwater County, Idaho. c.1950. Published as figure 87 in U.S. Geological Survey. Professional paper 344-A. 1962.