Magnetite, ilmenite, TiO2 minerals and haematite. Derbyshire, Britain
Euhedral equant magnetite (brown, left) enclosing silicate inclusions (grey, left centre) is overgrown by smaller magnetite crystals (centre left). Incipient alteration of magnetite is seen by lighter 'veinlets' cross-cutting it (left centre). An ilmenite lath is almost totally altered to a mixture of TiO2-rich (lilac-blue, centre) and higher reflectance haematite-rich phases (cream-white, centre). Minor relict ilmenite (pale brown) cores remain and unaltered ilmenite forms the lower rim to the lath. Subhedral pyroxene (light grey, internal reflections, top centre) and plagioclase (dark grey, bottom) form the silicate matrix.
Polished block, plane polarized light, x 160, oil