Granodiorite of De Luz Station
Field Collector: Esper Signius Larsen Jr.
Place Collected:De Luz Station, near Deluz CA, San Luis Rey Quadrangle, CA
Object number: ROC21680
DescriptionPlutonic, medium-grained (1-5 mm), igneous rock that is light brown on a fresh surface and grey-brown on a weathered surface. Consisting of 30% clear quartz (≤ 1 mm - 1 mm) that takes on a brown hue from the feldspars, 65% light-medium brown K-feldspar and plagioclase (≤ 1 mm - 4 mm), 3% black biotite (≤ 1 mm - 2 mm), and 2% black hornblende (1-3 mm). The feldspars were determined to be Olgoclase and Orthoclase in thin section, but are indistinguishable in hand sample.