An experimental study of the morphological evolution of pyrite under hydrothermal conditions and its implications

Occurrence Characteristics of Fine-Grained Pyrite in Coal and Its Scaling Effect on Flotation Desulfurization

“…Generally speaking, the pyrite crystals at the early and late stages of mineralization are mainly cubes (a {100}), and the pyrite crystals are dominated by pentagonal dodecahedrons (e {210}) and their aggregations in the intermediate stages. , The sulfur fugacity required for the formation of pentagonal dodecahedral pyrites and octahedral pyrites is larger than that of cubic pyrite. , When the medium state is saturated, the simple crystal form of a cube has a higher crystal face energy and can be formed easily, while the formation of pentagonal dodecahedron and octahedron crystals from the cubic crystal is relatively difficult because of the complex crystal structure and lower face energy. , In addition, Meng et al found that pyrite was more prone to form a combination of pentagonal dodecahedrons {210} and octahedron {111} at medium-high temperatures (210–220 °C) and in a sulfur-rich environment (S/Fe molar ratio of 4/1) …”

“…11,41 When the medium state is saturated, the simple crystal form of a cube has a higher crystal face energy and can be formed easily, while the formation of pentagonal dodecahedron and octahedron crystals from the cubic crystal is relatively difficult because of the complex crystal structure and lower face energy. 42,43 In addition, Meng et al found that pyrite was more prone to form a combination of pentagonal dodecahedrons {210} and octahedron {111} at medium-high temperatures (210−220 °C) and in a sulfur-rich environment (S/Fe molar ratio of 4/1). 43 According to the observation results of SEM, the pyrite crystals in Shanxi coal samples mostly appear in the form of cubic pentagonal dodecahedrons and cubic octahedrons, as shown in Figure 18a−c, indicating the abundant material supply for pyrite formation in the middle stage of mineralization; the metallogenic environment is continuous and stable, with a relative higher temperature (>200 °C).…”

“…42,43 In addition, Meng et al found that pyrite was more prone to form a combination of pentagonal dodecahedrons {210} and octahedron {111} at medium-high temperatures (210−220 °C) and in a sulfur-rich environment (S/Fe molar ratio of 4/1). 43 According to the observation results of SEM, the pyrite crystals in Shanxi coal samples mostly appear in the form of cubic pentagonal dodecahedrons and cubic octahedrons, as shown in Figure 18a−c, indicating the abundant material supply for pyrite formation in the middle stage of mineralization; the metallogenic environment is continuous and stable, with a relative higher temperature (>200 °C). Compared with the Guizhou coal sample, the Shanxi coal samples have more types of pyrite crystals, and their crystal structure is relatively complete.…”

Pyrite Dissolution in the Cretaceous Yogou Formation of the Niger (Chad) Basin: Implications for Basin Evolution under a Rift Tectonic Setting

“…Pyrite ( Py ), a naturally occurring iron disulfide (FeS 2 ) mineral, is quite common in marine and terrestrial sediment deposits. , Py can exist in many forms, such as euhedral pyrite (E Py ) crystals, pyrite framboids (F Py ), worm shapes, irregular masses, botryoidal-subspherical aggregates, fossil casts, and nodules , to its origins, − oxidation reactions, , morphological evolution, ,, and redox significance. , …”

“…1,2 Py can exist in many forms, such as euhedral pyrite (EPy) crystals, pyrite framboids (FPy), worm shapes, irregular masses, botryoidal-subspherical aggregates, fossil casts, and nodules. 3 Py has been extensively studied, from its elemental compositions 4,5 to its origins, 5−7 oxidation reactions, 8,9 morphological evolution, 5,10,11 and redox significance. 12,13 Two forms of Py, syngenetic and diagenetic, have been defined based on the interplay of the environment with reactions of sulfates, organic matter (OM), and reactive iron.…”