Figure 6. These views of thin sections from rocks bearing blue spinel (under plane-polarized light) show that blue spinel is always associated with olivine (forsterite) and pargasite in calcite matrix. Clinochlore surrounds all main minerals (left, field of view 1.5 mm). In the matrix, graphite and pyrrhothite are common accessory minerals (right, field of view 0.5 mm). Cc = calcite, Clh = clinochlore, Gph = graphite, Ol = olivine, Pg = pargasite, Pyr = pyrrhotite, Sp = spinel. Photomicrographs by Boris Chauviré.