{"title":"Martite","description":"\u003cp\u003e\u003cstrong\u003eMartite\u003c\/strong\u003e is not an independent mineral species but a variety of \u003cstrong\u003ehematite\u003c\/strong\u003e (Fe2O3) that has formed as a pseudomorph after \u003cstrong\u003emagnetite\u003c\/strong\u003e (Fe3O4), inheriting the octahedral or rhombododecahedral crystal habit of its parent while adopting the internal structure and reddish streak of hematite. This replacement process, known as \u003cstrong\u003emartitization\u003c\/strong\u003e, typically proceeds along the octahedral {111} planes and cleavage-like partings of magnetite, producing sharp, lustrous, silvery-black to steel-gray crystals that can be mistaken at a glance for true magnetite octahedra. The reverse transformation, magnetite pseudomorphic after hematite, is termed \u003cstrong\u003emushketovite\u003c\/strong\u003e, making martite and mushketovite a classic mineralogical pair illustrating iron-oxide phase transitions in nature. Martite was first described from \u003cstrong\u003eItabira\u003c\/strong\u003e, \u003cstrong\u003eMinas Gerais\u003c\/strong\u003e, Brazil, a region famous for its massive itabirite and banded iron formation deposits where martitization is a defining feature of the ore genesis.\u003c\/p\u003e\u003cp\u003eBeyond its Brazilian type locality, martite specimens of collector interest come from a wide range of iron ore districts and volcanic environments. The \u003cstrong\u003eKryvyi Rih Iron Ore Basin\u003c\/strong\u003e in Ukraine and numerous magnetite-quartzite deposits worldwide show martitization as a common secondary alteration feature of primary magnetite ore bodies. Striking fumarolic martite crystals, formed by high-temperature gas alteration of magnetite rather than by supergene weathering, are well known from the \u003cstrong\u003ePayún Matrú volcano\u003c\/strong\u003e in Mendoza Province, Argentina, and from the \u003cstrong\u003eMont Dore Massif\u003c\/strong\u003e in France, including the localities of \u003cstrong\u003ePuy de la Tache\u003c\/strong\u003e, \u003cstrong\u003eRoc du Cuzeau\u003c\/strong\u003e, and \u003cstrong\u003ePuy de Tunisset\u003c\/strong\u003e, where skeletal and twinned octahedra up to several centimeters have been recovered. Additional occurrences include \u003cstrong\u003eIron County\u003c\/strong\u003e, Utah, and historic material labeled from \u003cstrong\u003eDigby\u003c\/strong\u003e, Nova Scotia, once part of century-old European mineral collections.\u003c\/p\u003e\u003cp\u003eCollectors prize martite for its paradoxical nature: a crystal form unmistakably that of magnetite, yet chemically and structurally hematite, a tangible record of solid-state mineral transformation frozen in the specimen. Well-formed martite octahedra display an excellent metallic luster, sharp faces, and occasionally spinel-law twinning on {111}, features that distinguish fine museum-grade pieces from massive ore-grade material. Because martitization is intimately tied to the genesis of major iron ores, martite specimens also carry strong economic geology and petrological interest alongside their aesthetic and pseudomorph appeal, appealing equally to systematic hematite collectors, pseudomorph specialists, and students of iron-oxide mineralogy.\u003c\/p\u003e","products":[],"url":"https:\/\/www.italmineral.com\/collections\/martite.oembed","provider":"ITALMINERAL","version":"1.0","type":"link"}