Often referred to as a "variety" of either hematite or goethite, it is a mixture of the two minerals due to the alteration of goethite, typically found in the botryoidal habit of the "parent" goethite. It may be iridescent.
Turgite is a mixture of hematite and goethite, both iron oxide minerals. Since it is a mix, it is not recognized as a mineral. It apparently only occurs under specific environmental conditions because the pieces I collected in Nevada and brought home to New Mexico lost their luster and turned to dull gray hematite.