Mineralogical Composition: Felsic, Intermediat, and Mafic; Muscovite, Quartz, Potassium Feldspar, Plagioclase Feldspar, Amphibole, Biotite; Olivine, Pyroxene Texture (extrusive/intrusive): Extrusive; Glassy Other distinctive properties: Dark green to brown to black; Produced from rapidly cooled felsic lava