What is a trapezohedron in mineralogy ?
Trapezohedron : definition
A trapezohedron is a closed polyhedron with 6, 8 or 12 identical quadrilateral faces which results from the junction of two symmetrical open polyhedra. Depending on the number of faces, we speak of a trigonal (6 faces), tetragonal (8 faces) or hexagonal (12 faces) trapezohedron. In addition, there exists in the cubic system a trapezohedron with 24 faces, each of which is almost a trapezium (also called a tetragonotrioctahedron) of general form {hhl}, the most common being {112}.