Growing on a relatively open and 'slabby' rock slope lying within forested surroundings above the southeast end of Castle Lake. The geologic map here shows the location as underlain by purple coded as 'Op' = Trinity Peridotite (partially serpentinized). Upslope to the east on the map is a red area coded 'Mzg' = Mesozoic granitic rocks...which could have contributed to the surface material here via downslope erosion. Also upslope, but to the south is a blue area coded 'Ogp' = Gabbroic and dioritic rock (minor pyroxenite).