The fifth, the monoclinic-or clinorhombic, monosymmetric, or oblique-system, has also three axes, all of them unequal.
"The Chemistry, Properties and Tests of Precious Stones"
John Mastin
Orthoclase is orthoclastic and monoclinic; all the other feldspars are plagioclastic and triclinic.
"The Student's Elements of Geology"
Sir Charles Lyell