Named for Galena Point [a 4,400-ft hilltop in northeastern part of Galena Point 7.5' quad, Pend Oreille Co, WA] which is also the type locality (NE/4 sec.4 T34N R45E). The body appears elongate [underlies at least a few tens of sq mi] and extends beyond quad to the southeast (into ID) and to the north. Is typically porphyritic with euhedral K-feldspar crystals 0.5 to 2.5 inches long. Biotite is only dark mineral and composes about 12% of the rock. Contacts with wall rocks are irregular and ill defined owing to abundance of dikes that penetrate wall rock. Contact metamorphic aureole, a maximum of a mi in width, locally includes andalusite and cordierite. Intrudes Pritchard Formation of Belt Supergroup. K-Ar biotite age of 98.3 +/-3.2 Ma considered as age of emplacement inasmuch as mineral pairs from nearby plutons yield concordant ages. Assigned Cretaceous age.

Source: GNU records (USGS DDS-6; Menlo GNULEX).