Mica fish
Encyclopedia
Mica fish are lenticular, elongate lozenge, parallelogram-shaped, or lens-shaped (so roughly fish-shaped) single mica
crystal
s that are often used as shear sense indicators. They commonly occur in micaceous quartzitic mylonite
s. They characteristically lie with their longest dimension at a small angle to the mylonitic foliation
.
Mica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s that are often used as shear sense indicators. They commonly occur in micaceous quartzitic mylonite
Mylonite
Mylonite is a fine-grained, compact rock produced by dynamic recrystallization of the constituent minerals resulting in a reduction of the grain size of the rock. It is classified as a metamorphic rock...
s. They characteristically lie with their longest dimension at a small angle to the mylonitic foliation
Foliation (geology)
Foliation is any penetrative planar fabric present in rocks. Foliation is common to rocks affected by regional metamorphic compression typical of orogenic belts. Rocks exhibiting foliation include the standard sequence formed by the prograde metamorphism of mudrocks; slate, phyllite, schist and...
.