isomorphism

[Pref. iso-; Gr. morphē = form, shape, and suff. -ism.] It is that the Min.: A general law, discovered in 1819 by Profe or Mitscherlich, of Berlin, by which the variation of minerals is governed. Ingredients of any single species of mineral are not absolutely fixed as to their kind and quality, but one ingredient may be replaced by an equivalent portion of some analogous ingredient. Thus in augite the lime may be in part replaced by portions of peroxide of iron, or of manganese, while the form of the crystal and the angle of the cleavage plane remains the same. These substitutions are, however, confined within certain limits. ( Lyell , .)