In the Buruktal supergene nickel deposit, iron oxides possess vertical mineralogical zoning (bottom-up): magnetite-maghemite-goethite-hematite. The main rock- and ore-forming mineral in the iron-oxide zone of the deposit is magnetite, presented by three generations: primary relic magnetite, surviving from ultramafic rocks; secondary magnetite, forming at serpentinization process and neogenic supergene magnetite. Supergene magnetite, like a goethite, is nickel ore mineral, containing about 1 % NiO. Under the complex thermal analysis data, maghemite-magnetite and goethite have two main diagnostic maximums: exothermal effect of magnetite, caused by magnetite oxidation to maghemite in the interval 317‑340 °С, displays maximum at 327 °С («magnetite» point), and endothermic effect of goethite, connected with loss of constitutional water of the mineral and its transition to hematite in the interval 269‑296 °С, displays maximum at 288 °С («goethite» point).
