The fourth system, the rhombic-or orthorhombic, or prismatic, or trimetric-has, like the tetragonal, three axes; but in this case, none of them are equal, though the two lateral axes are at right angles to each other, and to the vertical axis, which may vary in length, more so even than the other two.
"The Chemistry, Properties and Tests of Precious Stones"
John Mastin
They are dark brown or yellow rhombic prisms.
"Aids to Forensic Medicine and Toxicology"
W. G. Aitchison Robertson
It operated with a rhombic antenna beamed to R.A.F. Calcutta.
"The Dawn of Amateur Radio in the U.K. and Greece A Personal View"
Norman F. Joly