Thin sections of two SMB samples. A) XPL and B) WDS Si map scan of HC01 from Spirit Mountain granite (SMG) unit, near the bottom of the section. Panel C and D are the same, for scans of BC02 sample from Spirit Mountain granite unit from the middle of the section. The main phases are quartz, biotite, plagioclase, and alkali feldspar (turquoise, orange, purple, and blue phases in right column, respectively).