Petrological and Mineralogical Studies of the Sibin Bian-Stone, a Material for Making Acupuncture Tools in Ancient China

Abstract

Bian-stone therapy has a long history of application in ancient China. Our recent studies reveal that Sibin bian-stone is a structurally compact micromeritic limestone with 96% (wt) CaCO₃. Its normal far-infrared (FIR) radiation power is as high as 0.923 in the 8–14 μm spectral zone. In order to investigate the relation between the mineral-constituent features and IR emission ability, a detailed mineralogical study of the bian-stone sample was conducted by using the Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). The Raman spectroscopic study confirmed the existence of 1–3-μm sized pyrite, anatase and graphite in calcite interstices and revealed two broad peaks of graphite being always present in the spectra of calcite, pyrite and anatase, respectively. HRTEM studies showed that the calcite grains are composed of numerous nanometre-sized crystals, with nanometre-sized graphite commonly occurring in calcite interstices. The occurrence of nanometre-sized calcite crystals is the most important mineralogical background accounting for the good thermal radiation property of the bian-stone. The common presence of nanometre-sized graphite enhances the thermal conductivity and heat-storing capability. The good pyroelectric property of pyrite, the good infrared absorption and reflection capability as well as the high photoelectricity transformation rate of anatase subordinately enhance the infrared radiation capability of the bian-stone. It is believed that the combination of good thermal properties of the above four minerals makes the Sibin bian-stone a useful material with very good physiotherapic functions.