First of all, we adopted the GRI G4 mining and metals sector reporting guideline. To our best knowledge, this isthefirst attempt that has been made to use GRI’s sector-focused reporting guideline for environmental disclosureanalysis. Second, we adopted afive-point scale from van Staden and Hooks (2007), and developed afive-point scalefor measuring corporate environmental reporting (see Table 2).Under GRI’s mining and metal sector disclosure guidelines, we selected environmental aspects. A total of 12 envi-ronmental aspects and 61 items were included. For each aspect of disclosure, a maximum score of 4 was assigned, ac-cording to the scale of van Staden and Hooks (2007). Hence, the overall maximum score for the disclosure index was244. The disclosure quality index is shown in Table 3, and combines different types of information, which Boutenet al.(2011) argue can be used as a valuable tool in assessing overall quality of environmental disclosure practice.