Mineralogical Characteristics and Colouring Mechanism of Hydrothermal Fluorite in the Sumochagan Obo Deposit, Inner Mongolia, north China
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-07-16 |
| Journal | Earth Sciences Research Journal |
| Authors | Zhan Lu, Liang Zhang, Zhixiong Chen, Biao Jiang |
Abstract
Section titled āAbstractāThe Sumochagan Obo fluorite deposit, located in the northern part of Siziwangqi, Inner Mongolia, is recognized as a world-class fluorite-only deposit. However, research on the mineralogical characteristics and genesis of fluorite in this area remains relatively limited. To further elucidate the coloring and formation mechanisms of fluorite in this region, this study investigates the mineralogical and spectral characteristics of green and purple fluorite using Diamond View, infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and laser Raman spectroscopy. Geochemical analysis was conducted using energy dispersive X-ray fluorescence spectrometry, wavelength dispersive X-ray fluorescence spectrometry, and inductively coupled plasma mass spectrometry (ICP-MS). In the ultraviolet-visible absorption spectrum, green fluorite samples exhibit absorption peaks at 223 nm, associated with Y and F centers. Absorption peaks at 693, 440, 360, and 276 nm are attributed to the presence of SmĀ²āŗ, while peaks at 587 and 591 nm are caused by calcium colloidal color centers. The purple color of fluorite is likely due to YOā centers, as indicated by absorption peaks at 276 and 261 nm in the ultraviolet-visible absorption spectrum of purple samples. Through the Tb/Ca-Tb/La plot, it is observed that most fluorite samples from this mining area fall within the hydrothermal zone, which aligns with geological observations. The measured total rare earth elements (āREE) of fluorite in this deposit fall between magmatic-hydrothermal fluids and meteoric water, indicating that the deposit was formed by the mixing of magmatic-hydrothermal processes with meteoric water involvement.