Crystal Systems and Mineral Classes Quiz

• The Triclinic System has only 1-fold or 1-fold rotoinversion axes.

• The Monoclinic System has only mirror plane(s) or a single 2-fold axis.

• The Orthorhombic System has only two fold axes or a 2-fold axis and 2 mirror planes.

• The Tetragonal System has either a single 4-fold or 4-fold rotoinversion axis.

• The Hexagonal System has no 4-fold axes, but has at least 1 6-fold or 3-fold axis.

• The Isometric System has either 4 3-fold axes or 4 3-fold rotoinversion axes.

• The Pedial Class is the only class in the crystal system that does not have symmetry.

• The Prismatic Class has 2 or more identical faces that are all parallel to the same line.

• The most common minerals in the prismatic class are the micas (biotite and muscovite), azurite, chlorite, clinopyroxenes, epidote, gypsum, malachite, kaolinite, orthoclase, and talc.

• This class of minerals includes andalusite, anthophyllite, aragonite, barite, cordierite, olivine, sillimanite, stibnite, sulfur, and topaz.

• These minerals are all related to each other by reflection or rotation about the horizontal 2-fold axes.

• Some of these minerals, like andalusite, are very common while others, like sillimanite, are less common.

Test your knowledge of crystal systems and mineral classes with this quiz. Learn about the different symmetry elements and common minerals associated with each class.