Gemmological Characteristic of “Anthophyllite Jade” from Xinjiang, China

The "anthophyllite jade" samples from Xinjiang, with two typical colour varieties (pink and dark green) were tested by conventional gemmological methods. X-ray powder diffraction spectrometer(XRD), Fourier infrared spectroscopy(FTIR), scanning electron microscope (SEM), laser induced breakdown spectroscopy(LIBS) and ultraviolet-visible spectrometry(UV-Vis) were used to analyze the chemical compositons, mineral components and microstructures and possible colour origins of the "anthophyllite jade" samples. The results showed that the pink "anthophyllite jade" samples from Xinjiang are composed of anthophyllite; while the dark green "anthophyllite jade" samples are tremolite. So it was incorrect to name "anthophyllite jade" by the standard of colour and structure features as Xinjiang's businessmen did. SEM result showed the dark green sample is typical nephrite felt structure and there were also parallel slender fibrous and columns, bringing out the part exquisite silk luster. Pink anthophyllite jade samples presented paralleled arrangement of coarser columns and slab structure, with bigger crystal sizes, leading to the visible obvious paralleled arrangement of coarser fibrous structure. LIBS results suggested the dark green colour may be caused by Fe and trace element C; and pink colour may be associated with trace element Mn.