SCHIST
Mica Schist - This schist clearly shows foliation as a layering in
the rock. Upon closer inspection of the mica shows that the sheets are
stacked in a very parallel manner. This is further indication of the the
influence of pressure acting on the rock.
Garnetiferous Mica Schist - Schists are often name according to
the conspicuous minerals that it contains. Here garnet crystals are
conspicuous.
Muscovite Mica Schist - This schist displays crenulations caused
by differential stresses. The foliation in a metamorphic rock forms
parallel to these stresses. In this sample there was more than on
direction of compressional force.
Tourmaline Mica Schist - Note the sub parallel alignment of the
tourmaline crystals. This is another example of foliation.
Schists represent a more elevated degree of heat and pressure that phyllites. Within the solid state, the micaceous minerals of the phyllite begin to rearrange their crystalline structure to form new minerals stable at higher temperatures and pressures. Foliation is still very evident by layering or the parallel alignment of mineral grains.
Here are some images of a field occurrence of Schist from the Buckeye Hills area of central Arizona.
Within this rubbly surface note the strike of parallel layers of schist.
This picture is of a small quarry about 100 feet south of where the above
picture was taken.
This image is a close up of the main layer of schist that was worked in
this area. The area around Buckeye Hills has numerous small scale workings
like this one. The schist was used in the manufacture of joint compound
for drywall.