The scale and persistence of severe adverse impacts is at odds with the widespread existence of company commitments, according to the RMI.
The RMI is an evidence-based index that assesses mining companies' policies and practices in six areas, including working conditions, the environment, economic development, business conduct and community wellbeing.
The index is from the Netherlands-based Responsible Mining Foundation.
The RMI surveyed 30 large mining companies that together operate more than 700 mines in more than 40 countries.
Those companies account for 25% of all mined commodities worldwide.
The index includes companies such as BHP Billiton, Rio Tinto, Glencore, Vale, Barrick Gold and Anglo American.
The six indicators are applied at a mine-site level for the individually selected 127 mine sites, which include Rio Tinto's Oyu Tolgoi mine in Mongolia, BHP's Escondida mine in Chile and Newcrest's Lihir gold mine in Papua New Guinea.
One area where mining companies' rhetoric does not match their performance at the mine site level is safe working conditions.
For example, worker fatalities continue despite nearly every company having made a commitment on occupational health and safety.
The 30 companies reported 331 worker deaths over the 2015 to 2016 period.
At the same time, the index shows the 30 companies are collectively demonstrating responsible mining across many issues and strong cases of leading practice are evident, providing valuable models for other companies.
The companies achieving the 10 strongest results vary substantially from one thematic area to another.
Overall, 19 of the 30 companies appear at least once, across the thematic areas.
"This indicates that performance does not depend on the size or commodity focus of companies, the countries where they operate, or the countries where they are registered," the report found.
"A company's performance in one area is not a strong predictor of its performance in other areas, nor of its overall performance."
The index found higher performing companies generally developed systematic, company-wide approaches to managing economic, environmental, social and governance issues.
"They could further improve their performance by applying similar systematic approaches to the full range of EESG issues," it states.
