If not enough heat and temperature were applied
another metamorphic rock could have been formed called phyllite,
which is not as hard as slate.
However, if the shale was in an area that was
exposed to higher pressures and moderate temperatures, it might have
been transformed into schist. The clay in the shale could have
been converted to mica, which gives schist its shiny look.
Granite is a light-colored rock made of quartz,
feldspars, mica, and small amounts of hornblende. The crystals of all
these minerals are randomly arranged. Granite can be metamorphosed into
a rock called gneiss (pronounced like "nice"). Gneiss
has about the same mineral composition as granite, but the pressure of
metamorphism causes the minerals to line up, giving gneiss a distinct banded
appearance. Schist may also be converted into gneiss, if increased
pressure and temperature is added. Metamorphic rocks are a mixed up
group that have been under a lot of stress!