Abstract
The chicken-blood stone is composed of "blood" and "substrate", in which the main mineral of "blood" is cinnabar and the main minerals of "substrate" are dickite, kaolinite, pyrophyllite, and alunite.To better identify the mineralogical characteristics between hard substrate chicken-blood stone from Changhua and its similar varieties, samples obtained from the market with real "blood" and fake "substrate" were studied in-depth. In this study, hard substrate Changhua chicken-blood stone and its similar varieties (from Xi'an, Guizhou, Qinghai and Sichuan) were collected. In order to study the mineralogical differences between hard substrate chicken-blood stone and its similar varieties, the main mineral composition, mineral assemblage characteristics, and chemical composition were obtained by polarizing microscope, X-ray powder diffraction (XRD) and electron probe microscope analysis (EPMA).In the studied samples, hard substrate Changhua chicken-blood stone contains cinnabar, quartz, illite, dickite, diaspore and pyrite. The cinnabar is massive and occurs as spotted distribution. The quartz is automorphic and silicification phenomenon is widespread and obvious in the hard substrate Changhua chicken-blood stone. The cinnabar exhibits metasomatic and parageneticcontact with quartz. The pyrite is automorphic, but seriously dissolved, and stellate distributed around cinnabar.The Xi'an "chicken-blood stone" contains quartz, cinnabar, dolomite, stibnite, pyrite and barite. The cinnabar presents granular aggregate and occurs as flake-like shapes showing massive and reticular distribution.The content of stibnite is low and there is no paragenetic contact between stibnite and cinnabar in the sample of Xi'an "chicken-blood stone"; The pyrite does not exhibit automorphic and is seriously dissolved, star-like distributing around cinnabar aggregate.The Guizhou "chicken-blood stone" contains quartz, cinnabar, stibnite and pyrite. The cinnabar presents disseminated and massive distribution.The pyrite shows automorphicmorphology with star and veinlets distribution characteristics, and the content of which is higher than that of compared samples.The Qinghai "chicken-blood stone" contains quartz, cinnabar, iron dolomite, and pyrite. The cinnabar in Qinghai "chicken-blood stone" occurs as obvious two-stage mineralization and presents cobweb and massive distribution characteristics. The quartz in the Qinghai "chicken-blood stone" shows obvious two-stage mineralization as well.The Sichuan"chicken-blood stone" contains quartz, cinnabar and a small amount of dolomite. The quartz exhibits automorphic with hexagonal morphology. The cinnabar shows scaly, massive, and veiny distribution patterns and its flash can be observed under oblique light.In addition, the cell parameters of the hard substrate Changhua chicken-blood stone and its similar varieties were calculated the data from XRD. The results show that the cinnabar of hard substrate Changhua chicken-blood stone and its similar varieties meet the structural characteristics of tripartite system, and the cinnabar in the hard substrate Changhua chicken-blood stone has parameters of a larger a-axis length and a shorter c-axis length, comparing to the cinnabar in the other samples.Through the comparative analysis of cinnabar by EPMA, it is found that there is no Cu in the cinnabar of the hard substrate Changhua chicken-blood stone and no Sb in the cinnabar of the Qinghai and Sichuan "chicken-blood stones". The Hg in the Guizhou, Qinghai, and Sichuan "chicken-blood stone" are likely replaced by a small amount of Fe, Ni, Cu and other elements.Through the analysis of energy spectrum and element content of the uncertain minerals in the samples, the cinnabar accompanying with barite can be observed in the Xi'an "chicken-blood stone". This study characterized the mineralogical characteristics of the hard substrate Changhua chicken-blood stone and its similar varieties from mineralogical point of view, which provided basic materials for the identification of chicken-blood stone and its similar varieties.
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