Using a LEITZ-II thermal microscope, thermal expansion characteristics of quartzite particles with different proportions of silicon dioxide (SiO2) were investigated at temperatures ranging from room temperature to 1600 degrees C. The experimental results showed that the thermal expansion of the quartzite particles with the temperature can be divided into three temperature regions, namely: the slow-expansion region, the temperature-independent region where the linear expansion coefficient tends to be zero and the fast expansion region with a sharp wave crest. A particle with high proportion of SiO2 (high purity particle) has higher melting characteristic temperatures and higher starting temperature of the fast-expansion region. In addition, the microstructure of high purity quartzite particles heated to different terminal temperatures were also observed through a HITACHI scanning electron microscope (SEM). Lots of micro-cracks (similar to 10 mu m wide on the sample surface and similar to 1 mu m wide inside the sample) can be formed at temperatures exceeding the starting temperature of the fast-expansion region. Calculating the residual deformations of the cooled particles which had been heated up to the different terminal temperatures indicated that these micro-cracks can greatly weaken the elasticity of the quartzite particles. (c) 2008 Elsevier B.V. All rights reserved.