The marble that hosts blue spinel has a granoblastic texture, with millimeter to centimeter grain size. SEM imaging with a backscattered electron detector showed exsolution features between calcite and dolomite, and intergrown apatite and calcite (figure 7a). Pentlandite lamellae in pyrrhotite present two different morphologies. The first consists of parallel flat lamellae less than 500 nm thick, crossing some pyrrhotite crystals from end to end. The second is lens-shaped, more than 1 µm thick and about 3 µm long, often associated with parallel flat lamellae (figure 7b).