High-temperature baked sandstone is widely distributed in the north of Shaanxi, China. The lithology of these rocks has a significant impact on the mining of underground resources such as coal. To understand changes in its physical properties after heat treatment, yellow sandstone was heated for two hour at a constant temperature of 25, 800, 1000, 1100 or 1250 °C. Data on the glossiness, hardness and colour brightness, and surface micrographs, were obtained to study the relationship between surface characteristics and temperature. The relationship between internal structural characteristics and temperature was studied using electrical properties and nuclear magnetic resonance (NMR) spectroscopy. The results showed that below 1100 °C, glossiness and porosity increased and conductivity, hardness and colour brightness decreased, mainly due to melting of the binder. Above 1100 °C, there was melting of clay minerals, quartz and feldspar particles, resulting in a sharp increase in the brightness and hardness of yellow sandstone, a sharp decrease in porosity, and glossiness and conductivity increase rarely. Combining these results with the surface micrographs, the whole thermal change mechanism could be summarised as follows: dehydration condensation of water-bearing minerals → melting of cement → melting of quartz and feldspar particles → pyro-metamorphism.

高温烘烤的砂岩在陕西北部广泛分布。这些岩石的岩性对诸如煤炭之类的地下资源的开采具有重大影响。为了了解热处理后其物理性质的变化，将黄色砂岩在25、800、1000、1100或1250°C的恒温下加热2小时。获得关于光泽度，硬度和颜色亮度的数据以及表面显微照片，以研究表面特性与温度之间的关系。使用电性能和核磁共振（NMR）光谱研究了内部结构特征与温度之间的关系。结果表明，在1100°C以下，光泽度和孔隙率增加，电导率，硬度和颜色亮度降低，主要是由于粘合剂的熔化。高于1100°C，粘土矿物，石英和长石颗粒熔化，导致黄色砂岩的亮度和硬度急剧增加，孔隙率急剧下降，而光泽度和电导率很少增加。将这些结果与表面显微照片相结合，可以总结出整个热变化机理：含水矿物的脱水凝结→水泥的熔融→石英和长石颗粒的熔融→热变质。