Integers used to designate crystallographic planes. They are found as
follows: (1) Determine where the plane intercepts each crystallographic
axis in terms of multiples of the axial parameters; (2) take the
reciprocals of these numbers and clear of fractions and common factors.
These three numbers, designated (hkl), are the Miller indices for that
plane. CF: Bragg indices; Miller-Bravais indices;
crystal indices; intercept. See also: symbols of crystal faces;
indices of a crystal face.
Dictionary of Mining, Mineral, and Related Terms