This paper examines an Australian garnieritic-type ore and changes in phase composition and morphology caused by heating in argon at 400-1000 degrees C using XRF, XRD, DTA/TG, SEM/EDS and BET analyses. The mineral phases detected by XRD in the original ore include chlorite, talc, hematite and quartz. Traces of iron silicate. Fe-Cr spinel and monoxide phase (predominantly manganese oxide) were observed by EDS. Nickel was detected in chlorite, talc, iron silicate and monoxide phase. Heat treatment at 400-500 degrees C did not change XRD patterns. At 600 degrees C, dehydroxylation of the brucitic phase of chlorite occurred. Chlorite was converted into olivine (forsterite) and enstatite at 600-800 degrees C. Upon heating to 900-1000 degrees C, talc was also converted into olivine and enstatite. Ni-bearing phases after heat treatment at 800-850 degrees C were forsterite, enstatite, talc, iron silicate and monoxide. (C) 2013 Elsevier Ltd. All rights reserved.