Quartz undergoes a reversible change in crystal structure from a to beta-quartz during its thermal treatment. Present study explored applicability of the phenomenon to break the phase interfaces between the quartz and other minerals present in siliceous manganese ores. Microscopic studies revealed that volume expansion of quartz initiates the fracture at phase interfaces. Detailed microscopic studies of fracture patterns reveal that these fractures can reduce the energy consumption during grinding and improve liberation of pyrolusite and quartz also. This approach is useful for processing of siliceous manganese ores and can be vital for processing of other siliceous ores also. (c) 2012 Elsevier Ltd. All rights reserved.