Green Valley Tonalite
Field Collector: Esper Signius Larsen Jr.
Place Collected:Near Vista California, USA
Object number: SLR 674
DescriptionBlack, white, and grey medium-grained (1-5 mm grains) plutonic igneous rock consisting of 46% plagioclase, 31% quartz, 10% perthite and orthoclase (K-feldspar), 8% biotite, 4% amphibole, 2% Fe-Ore (magnetite and/or hematite, and trace amounts of augite according to Larsen (1948).