rhomb

Rhomboid, rom′boid, n. a figure of the form of a rhomb: a quadrilateral figure having only its opposite sides and angles equal.

Let b x, c y (fig. 34) represent the section of an elongated rhomb of Iceland spar cloven from the crystal.

Let this rhomb be cut along the plane b c; and the two severed surfaces, after having been polished, reunited by Canada balsam.

Why did this pillow have to be placed so as to form a rhomb; and why did the girl's head have to rest exactly upon the diagonal?

Calcium carbonate crystallizes in the form of rhomb-shaped crystals which belong to the hexagonal system.