Boulder trail – pyterlite

Pyterlite is a unique type of rapakivi granite with a special quirk. Unlike typical rapakivi, where large round feldspar crystals (often egg-shaped) are surrounded by plagioclase rims, the crystals in pyterlite lack these rims. This difference makes pyterlite distinct from other rapakivi granite.

Named after the Pietarisaari area in Finland, this rock was historically mined there and transported to St. Petersburg, Russia, for use as building stone, giving it a long history of use.
Rapakivi, including pyterlite, is composed of quartz, potassium feldspar, plagioclase, and dark minerals like biotite.

Task: Closely examine the pyterlite rock, focusing on its polished surface. Find at least three differently shaped red crystals. Did you find them? If you compare wyborgite, rapakivi granite, and pyterlite, then what are some of the differences and some of the similarities in them?