“…The 91500 crystal has become by far the best characterised zircon RM currently available. Many authors demonstrated the reliability of their Hf isotopic data using this RM and LA-MC-ICP-MS (Chen et al 2008, Huang et al 2008, Liu et al 2008a, Murgulov et al 2008, Sláma et al 2008, Tang et al 2008a, Ushikubo et al 2008, Yang et al 2008a, b, Yuan et al 2008, Zhang et al 2008b, Howard et al 2009, Iizuka et al 2009, Kemp et al 2009). There is some debate, however, as to whether 91500 zircon is heterogeneous in its 176 Hf ⁄ 177 Hf ratio, with a probably bimodal distribution being suggested (Griffin et al 2006).…”