"Orthorhombic. Crystals resemble closely those of barite. Commonly tabular parallel to the base or prismatic…

"A crystal has a center of symmetry if an imaginary line is passed from some point on its surface through…

"Habit varied and crystal show many forms. Crystals often tabular parallel to brachypinacoid." —…

"Hexagonal-rhombohedral. Common form is the simple rhombohedron, r, having nearly cubic angles. May…

"Orthorhombic. Usually in small tabular crystals with hexagonal outline. Striated parallel to the brachy-axis.…

"A drawing of a crystal showing a combination of the cube, octahedron and rhombic dodecahedron is shown,…

"Orthohombic. Habit of crystals is short prismatic; often in square prisms because of prominent development…

The combination of icositetrahedron and rhombic dodecahedron.

The combination of an icositetrahedron and an octahedron.

Represents the combination of pentagonal dodcahedron, dyakis-dodecahedron and octahedron.

"...shows the rhombic dodecahedron in combination with the octahedron." -The Encyclopedia Britannica…

"...a combination of these two tetrahedra, and represents a crystal of blende, in which the four larger…

"Hexagonal-rhombohedral. Crystals usually prismatic in habit or tapering hexagonal pyramids." —…

"Hexagonal-rhombohedral. Crystals usually prismatic in habit or tapering hexagonal pyramids." —…

"...represents a crystal of augite bounded by th clino-pinacoid, the ortho-pinacoid, a prism, and a…

"Here there is only a [center] of symmetry. All the forms are pina-coids, each consisting of only two…

"...a combination of two bisphenoids (P and P'), two bipyramids of the second order (b and c), and the…

"...represents a crystal of dioptase with the fundamental rhombohedron (r) and the hexagonal prism of…

"...a combination of tetragonal prism of the first order with a tetragonal bipyramid of the third order…

"...a combination of the brachy-pinacoid and a prism, with the pedion, two brachy-domes and two marco-domes…

"...represents a crystal of tourmaline wit the trigonal prism, hexagonal prism, and a trigonal pyramid…

"...shows the actual shape of a crystal of ziron from Ceylon" -The Encyclopedia Britannica 1910

"...the ideally developed form [of a zircon crystal]. The crystal is a combination of five simple forms:…

"The forms present upon it are two pyramids of different slope but each intersecting all three of the…

"...take any three edges formed by the intersection of three faces of a crystal. These axes are called…

"Science has succeeded in classifying the thousands of known crystals in six systems, to each of which…

Represents the combination of an octrahedron and a cube, with the cube faces predominate.

Represents the combination of a cube and an octahedron, with both faces being equal.

"Monoclinic. Habit varied. Crystals usually nearly equidimensional in the three axial directions and…

"This is the hemihedral form of the triakis-octahedron; it has the indices {hhk} and is bounded by tweleve…

The diamond is cut to show the stone's brilliance, creating different parts to the cut: table, crown,…

Various types of square cut diamonds. Top row: Old square cut diamonds. Bottom row: English square cut…

"...bounded by twenty-four scalene triangles...This form may be considered as a combination of two scalenohedra,…

Diopside is a monoclinic pyroxene mineral with composition MgCaSi2O6. It forms complete solid solution…

"Hexagonal-rhombohedral. Crystals are usually the unit rhombohedron (cleavage rhombohedron). Faces often…