The above may be illustrated by considering the equilibrium between rhombic and monoclinic sulphur.
monoclinic crystals common, usually of simple forms, as shown by Figure 75i.
Below this temperature the octahedral, above it the monoclinic, is the stable form.
Sulphur exists in two well-known crystalline forms—rhombic, or octahedral, and monoclinic, or prismatic sulphur.
Pyroxenes crystallizing in the monoclinic system are the most important.
At any point outside this area, monoclinic sulphur can exist only in a metastable condition.
A hydrous silicate of magnesia never in distinct crystals as such, but shown to be monoclinic under the microscope.
The monoclinic crystals are prismatic in habit, with deeply striated prism and dome faces.
The crystals are monoclinic and occur in porphyry almost exclusively.
Occasionally, though but rarely, malachite occurs in small dark-green prismatic crystals of the monoclinic system.
Relating to a crystal having three axes of different lengths. Two of the axes are at oblique angles to each other, and the third axis is perpendicular to the plane that is made by the other two. The mineral gypsum has monoclinic crystals. See illustration at crystal.