Euhedral to subhedral zoned oligoclase to andesine plagioclase and anhedral quartz, in small pods, are the primary constituents of the rock. |
Plagioclase is often replaced by alkali feldspar and varies in composition from andesine to oligoclase. |
These intermediate members are the lime-soda felspars known as oligoclase, andesine, labradorite and bytownite. |