GEOL 3235 : Introduction to Petrography

Laboratory 4 - Metamoprhic Rocks

The rocks for the exercise on Metamorphic Rocks are stored in the wooden trays.

Prepare a Table with the following columns -- Sample Number -- Gross Characteristics -- Name -- Protolith. Look at each sample. Are these metamorphis rocks? For gross characteristics determine if the rock is homogeneous or heterogeneous -- or non-mineralogically banded or mineralogically banded.

Determine if the rock is anisotropic -- has some form of oriented minerals or isotropic. Gneisses are heterogeneous - banded. It does not matter whether the minerals or anisotropic or isotropic.

Non-banded isotropic metamorphic rocks are either hornfels (fine grained) or granofels (coarse grained). Non-banded anisotropic metamorphic rocks are slates, phyllites, or schists -- function of grain size.

Modify the "gross characteristics" name with any minerals present -- a talc schist or a quartz-feldspar-quartz gneiss.