Yellow iron oxide (FeO(OH).H2O) supplies Fe2O3.  It is an Ochre-colored iron oxide, nit to be confused with yellow ochre, which is a naturally-occurring impure mixture of yellow iron oxide, clay, etc.  It is clay impregnated and dissolves
more readily in the glaze matrix than Red Iron Oxide.  It is about
75% as strong as Red Iron Oxide. In saturation, it goes maroon instead of
metallic.