Contact between above dike and amphibolite. A coarse black rock carrying magnetite and pyrites in considerable quantities.
Under the microscope some of the biotite has a green coloration from decomposition and is surrounded by strong pleochroic halos.
Small grains of secondary pyroxene are numerous.
AMPHIBOLITE
3-Grand Lake.
A dark, compact rock, having a mottled appearance due to grains of plagioclase, and a green color in section.
Minerals present are hornblende, biotite, plagioclase, pyroxene, quartz and the alteration products from the feldspar.
The rock has been subjected to a strong crushing action, which has been resisted by only small portions of it. The spaces between the grains, which are intact, are filled with a confused mass of peripherally granulated minerals, in which strain shadows are very prominent.
The rock has been derived by dynamic metamorphism from a basic igneous rock.
4-Biotite Granite Gneiss.