TiO2 minerals and sphene. Central Wales, Britain
A metadolerite in which a trellis-like intergrowth of a TiO2 mineral (light grey), often called 'leucoxene', has replaced ilmenite lamellae within a titanomagnetite which has been completely removed and is represented by iron-stained non-opaque minerals showing brown internal reflections. The original titanomagnetite aggregate can be seen to have comprised two crystals. Sphene (light grey, centre right) is present. The matrix is silicate.
Polished block, plane polarized light, x 160, oil