Study on Composition Characteristics of Reddish Brown Series of Larderite

The larderite is named after Shoushan area located at northern outskirts of Fuzhou near 30 km.In recent years,the market price of the larderite has been rising steeply when the larderite is nominated for one of the national stones in China.In the paper,the mineral compositions of the reddish brown series of the larderite samples are generally studied by means of the conventional gemmological testing,X-ray powder diffraction and FTIR.According to the main mineral compositions,the larderite samples could be classified into three types,including kaolinite,pyrophyllite and illite.The results indicate that the main mineral compositions and sorts of the larderite could be confirmed by its relative density.