What causes mining asset impairments?

When the recorded value of an asset on a mining company's balance sheet exceeds its market value or its value in use, an impairment must be declared. While impairments have been shown to be a common occurrence across mining companies, they also are a major contributor to the industry's low average returns. To better understand the causes and predictors of mining impairments, we collected and analyzed the 266 impairments declared by TSX-listed mining firms between 2002 and 2015. As to the stated reasons for impairments, we find that declines in metal prices account for over half of all impairments, with none of the other eight categories representing more than 13%. To identify factors that might predict future impairments, we drew on the literature on major infrastructure projects. Consistent with this literature, we find that the degree of impairments is higher at mines in developing countries and at mines where the geographic location and mining processes are new to the company operating the mine. Our findings point to several dimensions along which mining firms should seek to improve their forecasting processes.