The ratio (I_p) of charge (z) on an ion to the radius (r) of the ion, I_P = z/r.

An obsolete, local term for a kaolin forming crusts in the Ione sandstone, California, USA.

See hydrotalcite group.

An obsolete term for annite, siderophyllite, biotite, and hematite.

An invalid name for a hypothetical end member.

An obsolete varietal term for ferrian illite.

An obsolete varietal term for lithian muscovite.

An obsolete term for muscovite.

Isomorphous literally means “having the same form”. The idea was first described by F. Beudant around 1800 (see Zoltai and Stout, 1984, p. 5-6) to describe crystals having the same form but having compositions between FeSO₄ and ZnSO₄. Thus, the term subsequently became commonly used to describe a series of crystals having continuously varying composition even where crystal faces are lacking. Such homogeneous chemical mixtures display a continuous range of properties, e.g., from the Fe to Zn end members. Such a series of solids is referred to as an “isomorphous substitution” series (archaic) or “solid solution” series. See “solid solution” for additional discussion.
Isomorphic (syn)

a description of material with physical properties that are the same regardless of direction of measurement. Cf., anisotropy