The mineral matter of coal contains a number of inorganic constituents. which play an important role in almost all coal utilisation systems. Some techniques have been applied to coal to separate its mineral matter from its organic part. In this study, an alternative method was applied to separate the mineral matter content of a Turkish lignite. For this purpose, Goynuk lignite was treated, in sequence, with acetic acid, ammonia, hydrochloric acid, hydrofluoric acid and nitric acid at 70 degreesC for 60 min in order to remove individual mineral species. After each stage, the lignite was treated with performic acid, the product of reaction between hydrogen peroxide and formic acid, at 50 degreesC. The organic coal matrix was decomposed as a result of performic acid oxidation, and consequently, the recovered mineral species were isolated. Ammonia, which has the potential of chemical comminution, was used to increase the effects of the subsequent reagents and enhance the extent of separation between the organic and inorganic phases. In each mineral matter removal stage, the lignite was treated with the reagents of the previous stage, and then, a new reagent was added to investigate whether the last stage has a different effect on the mineral species. FT-IR and X-ray diffractometry techniques were used to determine the constituents of the isolated mineral matter after each stage. (C) 2001 Elsevier Science Ltd. All rights reserved.