The following thin sections are arranged to review the principal rock-forming minerals. Note that under each main mineral-heading other minerals are included. Questions to be answered for this lab are underlined. Finely perthitic orthoclase is present in minor amount. Estimate 2V and sign in abundant orthopyroxene to determine its composition .
Plagioclase is abundant as large crystals.
Plagioclase is abundant as coarser phenocrysts and as very fine-grained laths in the matrix. Minor olivine is present. Orthoclase is microperthitic and intergrown with quartz. Both appear to be optically continuous as megacrysts. There are also occasional crystals of muscovite and plagioclase.