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Illustration showing a trigonal dodecahedron.

Trigonal Dodecahedron

Illustration showing a trigonal dodecahedron.

This form shows a rhombic dodecahedron (d) combined with the trigonal tristetrahedron (q). It sometimes occurs on Zincblende.

Rhombic Dodecahedron Combined With the Trigonal Tristetrahedron

This form shows a rhombic dodecahedron (d) combined with the trigonal tristetrahedron (q). It sometimes…

This crystal of Tourmaline exhibits hemimorphism in the direction of the vertical axis. Its forms are the prisms, (g), which as a result of hemimorphism, appear as a trigonal prism, and (a); the scalenohedron, (s), and the two rhombohedrons, (R) and (r), at the antilogue pole, while only (R) occurs at the analogue pole.

Tourmaline

This crystal of Tourmaline exhibits hemimorphism in the direction of the vertical axis. Its forms are…

"...bounded by six isosceles triangles...indices as in the hexagonal bipyramid." -The Encyclopedia Britannica 1910

Trigonal Bipyramid

"...bounded by six isosceles triangles...indices as in the hexagonal bipyramid." -The Encyclopedia Britannica…

"...bounded by six trapezoidal hedra...derivable from the scalenohedron." -The Encyclopedia Britannica 1910

Trigonal Trapezohedron

"...bounded by six trapezoidal hedra...derivable from the scalenohedron." -The Encyclopedia Britannica…