Demicheleite-(I), BiSI, a new mineral from La Fossa Crater, Vulcano, Aeolian Islands, Italy

Abstract

Demicheleite-(I), ideally BiSI, is the iodine-dominant analogue of demicheleite-(Br) and demicheleite-(Cl). It was found in an active medium-temperature intracrateric fumarole at La Fossa crater, Vulcano Island, Aeolian archipelago, Sicily, Italy. The mineral is the first bismuth sulphoiodide so far discovered in a wholly natural environment, and corresponds to the already known synthetic compound. It occurs as acicular to stout, translucent crystals up to 0.25 mm long in an altered pyroclastic breccia, together with demicheleite-(Br), bismoclite, bismuthinite, godovikovite, panichiite, aiolosite, brontesite, adranosite and other new phases under study. The colour is dark red to black, the lustre submetallic. The unit cell is orthorhombic, space group Pnam, with a = 8.4501(7) Å, b = 10.1470(9) Å , c = 4.1389(4) Å , V = 354.88(4) Å3, and Z = 4. The crystal habit is prismatic, with the main forms {110} and {111} inferred from analogy with demicheleite-(Br). Twinning was not observed. The strongest 6 lines in the X-ray powder diffraction pattern [dobs.(Å) (I/I0) (hkl)] are: 6.490 (100) (110); 4.346 (94) (120); 3.896 (90) (210); 2.709 (60) (310); 2.161 (38) (330); 3.243 (22) (220). The chemical analysis obtained by WDS electron microprobe gave: Bi 58.32, S 9.43, I 23.69, Br 5.66, Cl 1.01, totalling 98.11 wt.%, corresponding to an empirical formula (based on 3 a.p.f.u.) of: Bi0.97S1.03(I0.65Br0.25Cl0.10)Σ1.00. The unit-cell data are close to those of the synthetic compound, whose crystal structure is already known. The calculated density is 6.411 g cm–3.

Optical, electronic, and elastic properties of some A5B6C7ferroelectrics (A=Sb, Bi; B=S, Se; C=I, Br, Cl): First principle calculation

“…Therefore, the geometric optimization process is performed to detect that the structure is the correct structure. The lattice parameters obtained as a result of optimization are given in Table 1 [29,30,[33][34][35][36][37][38].…”

“…Such a low value is a good indicator for an adequate convergence of the calculations. [30][31][32][33][34][35][36][37][38][39]. The atomic positions belonging to these compounds are given in Table 1.…”

1D SbSeI, SbSI, and SbSBr With High Stability and Novel Properties for Microelectronic, Optoelectronic, and Thermoelectric Applications

“…Bulk V-VI-VII semiconductor has an orthorhombic structure with the space group of Pna2 1 , www.advancedsciencenews.com www.advtheorysimul.com and crystallizes in 1D chains which are held together by van der Waals interaction. [17] Bulk V-VI-VII semiconductors are earth abundant materials, [18,19] and with chained structures, these materials may be good precursors for 1D crystals by exfoliation or mechanical cleavage. [20] However, due to the lack of knowledge on the properties of 1D V-VI-VII compounds, little research has been conducted on the isolation of the chain.…”

Raman spectroscopic study of six synthetic anhydrous sulfates relevant to the mineralogy of fumaroles

“…Subsequently, this mineral was discovered at several coal fire localities: the Schoeller mine, Kladno, Czech Republic, the Czerwionka‐Debiensko dump, Poland, the Anna mine, Alsdorf, Germany, the Ikushnubetsu area, Mikasa, Japan, and the Wuda coalfield, northern China . Godovikovite was also identified within uncommon fumarole assemblages in the La Fossa crater, Vulcano Island, Sicily . In fact, godovikovite is probably one of the most widespread ammonium‐bearing sulfate at burning waste dumps.…”