[1] Fangite was detected in an isolated vug of sulfide ore stockpile within the Morrin Hill pit at the Mercur gold deposit.
Based on surrounding materials, it can be concluded that Fangite forms as a result of alteration of thallium sulfates or by substituting fluids that are Ti-rich for realgar or orpiment.
When examining fangite in a polished section, only one grain could be used to test optical properties due to the abundant presence of internal red reflections.
The consistent decrease in reflectance from the blue to red end of the visible spectrum aligns with the blue-gray appearance of fangite in polished sections.
Comparing these reflectance spectra with those in the Quantitative Data File for ore minerals reveals similarities between R1 and R2 of fangite and the R2 values of proustite (Ag3AsS3).
Arsenic (As) atoms in this orientation display perfect tetrahedral coordination with Sulfur (S) featuring an average bond length of 2.172 Å.
A distorted trigonal dipyramid with an average bond length of 3.17 Å is formed with the Thallium (Tl) atom, coordinated in a fivefold manner with S. The Thallium (Tl) atom is also coordinated sevenfold with Sulfur (S), creating a monocapped octahedron with an average bond length of 3.288 Å.