Figure 6.
Reflected light, crossed Nicols. Optical micrographs of the thermally treated samples: (a) NV4-TT; (b) NV5-TT, Hematite (white, red internal reflections), magnetite (gray); (c) NV6-TT, Hematite (white, red internal reflections), magnetite (gray); (d) NV7-TT, Magnetite (gray), hematite (white, red internal reflections).