Gemmological Characteristic and Genetic Mineralogy on Pyrite-Chlorite-Bearing Actinolite Jade

Pyrite-chlorite-bearing actinolite jade, that has dark green colour with yellow minerals disseminated in it, is a new kind of jade appearing in the market. In order to deeply understand the structure, mineral components, and genetic information of the pyrite-chlorite-bearing actinolite jade, X-ray diffractometer, polarizing microscope, scanning electron microscope, electron probe micro-analyzer, and other test methods were employed. The results showed that: (1)The main mineral components of the pyrite-chlorite-bearing actinolite jade were trioctahedral chlorite (45%), actinolite(45%), and pyrite(10%); (2)The actinolite was fibrous crystalloblastic structure and the chlorite was of lepidoblastic texture, with pyrite embedded in the jade composed of chlorite and actinolite; (3)Plots of the major elemental components of actinolite in the Mg/(Mg+Fe²⁺)-Si of tremolite-actinolite-ferroactinolite classification diagram was within the range of actinolite.The sample chlorite in the Fe-Mg-(Al+□) classification diagram was plotted within the range of amesite and Type Ⅰ trioctahedral chlorite; (4)The values of the Mg/(Mg+Fe²⁺)≈0.89 of the actinolite and the Al/(Mg+Fe) < 0.35) and the Mg/(Mg + Fe) =0.85) of the chlorite indicate that the protolith of the sample is magnesium-rich ultrabasic rock; (5)By predicting the formation environment based on the typomorphic chemical composition of chlorite, the result showed that the sample was formed in a relatively reduced environment of medium and low temperature and should have undergone multistage metamorphisms during the formation process. Considering the pyrite-chlorite-bearing actinolite jade contains substantial content of chlorite, as well as the environment of formation which are different from nephrite, the pyrite-chlorite-bearing actinolite jade studied here was not recommended to name as Hetian Yu according to the current national standard.It is suggested that the sample may named as actinolite jade (containing chlorite).