M. Wintenberger et al., MAGNETIC-PROPERTIES OF GREEN DIOPTASE CUSIO3H2O AND OF BLACK DIOPTASECUSIO3, AND MAGNETIC-STRUCTURE OF BLACK DIOPTASE, Solid state communications, 87(4), 1993, pp. 309-312
The rhombohedral (R3BAR) compounds green dioptase, CuSiO3H2O, and blac
k dioptase, CuSiO3, are both antiferromagnetic. Their Neel temperature
s are respectively near 50 and 110 K. The magnetic structure of the an
hydrous compound has been studied by powder neutron diffraction. The m
agnetic moment of Cu is of order 0.5 muB.