GOTHITE, or Goethite, a mineral composed of an iron hydrate, Fe203.H20, crystallizing in the orthorhombic system and isomorphous with diaspore and manganite.
Crystals of barytes are orthorhombic and isomorphous with the strontium and lead sulphates (celestite and anglesite); they are usually very perfectly developed and present great variety of form.
It crystallizes in octahedra isomorphous with stannic oxide.
More useful is the property of isomorphous substances of forming mixed crystals, which are strictly isomorphous with their constituents, for all variations in composition.
9 illustrates the first case: the ordinates represent specific volumes, and the abscissae denote the composition of isomorphous mixtures of ammonium and potassium dihydrogen phosphates, which mutually take one another up to the extent of 20% to form homogeneous crystals.