Alkali Feldspar Granite Thin Section Photos. Click on any photo for a larger image. Some of the larger images may be on other web sites and will open in a new window.

Cape Ann Granite Thin Section

afgts_001. Thin section of the Cape Ann Granite in plane polarized light (ppl). The cloudy gray minerals are alkali felspar (microperthite). The colorless mineral is quartz. The dark green to brown minerals are an iron-rich clinopyroxene (aegirine) and an iron-rich amphibole (arfvedsonite).