Gemological Characterization Of The Rare Mineral-Pyromorphite In Guangxi And The Research Ofusing Pmma To Reserve It

High quality Pyromorphite which was found in Guangxi in 2001 is a rare kind of mineral crystal in China. The molecular formula of Pyromorphite is [Pb5 (PO4) 3cl],belongs to apatite tribe. Each Cl~ is regularly surrounded in the same level by there Pb2+ ions so that the ions at any position of this crystal can be substituted. Ca2+ in apatite structure can be substituted by the first tribe, the second tribe and the third tribe as well as Ca, Cd, Zn, Sc, Y, Cr, Fe, REE, Bi etc., PO43- can be substituted by SiO44-, SO42-, VO43-, CO32-, AsO43-, CrO42- etc, and the channel-ions can substitute each other such as F-, Cl-, OH-, CO32- etc..In this paper, the samples with yellow and green color are researched by X-ray powder diffraction (XRD), X-ray fluorescence (XRF), Infrared spectra (IR) and Ultraviolet-visible spectra(UV-Vis). We get the following results: the difference between the twe kinds samples is peak strength; in IR spectra, twe shoulder peaks between 670cm-1-800cm-1 and 430cm-1 are antisymmetric stretching and bending vibrational peak of SiO44-, yellow samples have higher vibrational frequency, thinner half width and higher transmittance comparing with green samples; it's known that Fe3+ make the mineral yellow, and more isomorphism phenomenon and more Fe3+ are found by XRF in yellow pyromorphite, at the same time, it's confirmed that the reason of more higher IR frequency in yellow pyromorphite is that it has lower Pb content. UV/Vis is used to confirm that the different absorbance makes the sample's color difference.Pyromorphite is a kind of rare decorative minerals, so it is a good method to reserve the pyromorphite by covering it into PMMA. The method can improve the ornamental. This paper introduces the preparation of the sample, mould-making and the process of producing and analyzes the reasons of generating different product.