Although not carbonates, a characteristic of these minerals is parallel extinction under cross-polarized light, which has a "mottled" or "bird's eye" appearance.
The weathering of one example of this group of minerals yields the clay vermiculite. Although not carbonates, a characteristic of these minerals is parallel extinction under cross-polarized light, which has a "mottled" or "bird's eye" appearance. Like its mother group, this group of minerals can be split based on whether they are dioctahedral and trioctahedral, which gives them colors of white and black, respectively. These minerals are the main components of schist and contribute to its namesake foliation. These minerals can be cut into thin lamellae because they easily split parallel to their bases and many exhibit perfect basal cleavage. For 10 points, name this class of phyllosilicate minerals that includes lepidolite, muscovite and biotite.
The weathering of one example of this group of minerals yields the clay vermiculite.
micas [prompt on phyllosilicate or sheet silicate minerals]