Ferrite

ferrite transition zone

Technical terms like ferrite, perlite, graphite, and hardenite were bandied to and fro, and when Paget glibly brought out such a rare exotic as ferro-molybdenum, Benson forgot that he was a master ship-builder, […]

ferrite magnets

The actual hardware is obsolete; for example, the memories are of the old ferrite core type.

sodium ferrite

calcium ferrite