In situ Raman spectroscopic studies of FeS₂ pyrite up to 675 K and 2100 MPa using a hydrothermal diamond anvil cell

Abstract

Raman scattering experiments of natural FeS2 pyrite were performed at simultaneous high-pressure and high-temperature conditions up to 675 K and 2100 MPa using a hydrothermal diamond anvil cell combined with micro-Raman spectroscopy. Four out of five Raman active modes [Eg, Ag, Tg(1) and Tg(3)] were resolved at ambient conditions, the remaining Tg(2) [∼377 cm–1] mode was weak and unresolved occurring ∼2 cm–1 from the intense Ag [379 cm–1] mode. The frequency shifts of the Eg [343 cm–1] and Ag [379 cm–1] modes were determined to be quadratic functions of pressure and temperature: ν343 = 343.35 – 0.0178 × ΔT – 8.4E – 6 × (ΔT)2 + 0.00367 × Δp 3.7E–7 × (Δp)2 + 1.0E–6 × ΔT × Δp and ν379 = 379.35 – 0.0295 × ΔT – 9.0E–6 × (ΔT)2 + 0.00460 × Δp – 5.3E–7 × (Δp)2 + 7.0E–7 × ΔT × Δp. The positive pressure dependence of both modes indicates stress-induced contraction of S–S and Fe–S bonds, whereas the negative temperature dependence shows temperature-induced expansion of them. The Raman spectra of pyrite were used to derive its bulk modulus at high temperatures, thermal expansion coefficient at high pressures and anharmonic parameters at high-pressure and high-temperature conditions.

EMPA, XRD, and Raman Characterization of Ag-Bearing Djurleite from the Lubin Mine, Lower Silesia, Poland

“…In the Raman spectrum of anhydrite, the following bands were distinguished: 123 cm −1 , 151 cm −1 , 168 cm −1 , 230 cm −1 , 268 cm −1 , 415 cm −1 , 499 cm −1 , 609 cm −1 , 626 cm −1 , 675 cm −1 , 1017 cm −1 , 1111 cm −1 , 1127 cm −1 , and 1158 cm −1 , while for pyrite, the characteristic vibrations bands at 347 cm −1 , 381 cm −1 , and 432 cm −1 are visible. The above described Raman spectra are typical for these minerals, and they not differ from the literature data [31][32][33][34][35][36][37]. The obtained Raman spectrum for bornite (which was confirmed by EMPA data) shows two wide bands in the region between 200 and 400 cm -1 , which corresponds to the bands visualized in all of the available bornite Raman spectra (among others, the RRUFF Database; [35]).…”

Source and Enrichment of Toxic Elements in Coal Seams around Mafic Intrusions: Constraints from Pyrites in the Yuandian Coal Mine in Anhui, Eastern China

“…In the Raman spectra analysis, the Eg (322.3-326.2 cm −1 ) and Ag (386.4-396.3 cm −1 ) of pyrites in unaffected coal matched the reported frequency modes of marcasite [54][55][56], and the Eg (343.0-344.2) and Ag (377.4-380.6) of samples from diabase, aureole and cokeite shifted toward higher frequencies relative to the Eg (343) and Ag (377) of pyrite in the published Renishaw database [54][55][56][57][58]. This indicates that Py I may have deposited under relatively low temperatures [57][58][59]. The intensity ratios of Eg to Ag in pyrites increased away from the intrusion-the Eg values increased from 264.1-754.4 in Py II to 699.0-1273.5 in Py IV, whereas the Ag values decreased from 678.9-1243.2 in Py II to 531.0-1099.5 in Py IV.…”

“…The intensity ratios of Eg to Ag in pyrites increased away from the intrusion-the Eg values increased from 264.1-754.4 in Py II to 699.0-1273.5 in Py IV, whereas the Ag values decreased from 678.9-1243.2 in Py II to 531.0-1099.5 in Py IV. This indicates that the formation temperatures and pressures of Py II were higher than those of Py IV [56][57][58][59], as the intensity of Eg is negatively correlated with pressure, whereas the intensity of Ag is positively correlated with temperature [56][57][58][59]. Therefore, the pyrites enclosed in pyroxene and plagioclase (in diabase) have likely high formation temperatures [53][54][55], whilst the pyrites in the cokeite have likely low formation temperatures [53][54][55][56][57][58].…”

The Characteristics and Origin of Amber Deposits in the Dominican Republic

“…White mica (muscovite) forms single, ne plates randomly scattered within the rock matrix. Pyrite manifests its abundant presence in the rocks by three diagnostic bands at 432, 378, 343 cm − 1 in the Raman spectra [42][43][44] . It forms at least three morphological types: (1) framboidal, (2) recrystallized and (3) euhedral crystals.…”