The crystallographic stability and anisotropic compressibility of C54-type TiSi2 under high pressure

et al. 2023

American Mineralogist

temperature of the 4 minerals in the spheroid wenjiite → kangjinlaite → zhiqinite + badengzhuite is consistent with relationships reported in 9 binary systems containing intermetallic compounds of Ge and Sn isostructural with Mn 5 Si 3 and Ho 11 Ge 10 , in 8 of which the Mn 5 Si 3 analogue melts congruently, whereas the Ho 11 Ge 10 analogue never does. Instead the Ho 11 Ge 10 analogue melts peritectically, generally to an Mn 5 Si 3 analogue and less commonly to compounds with 5:4 stoichiometry. Final crystallization of the spheroid to zhiqinite + badengzhuite is expected to be well below the temperature of 1500 °C for the congruent melting of zhiqinite in the Ti-Si system, i.e. in the range of ~1100 -1300 °C.

Section: Kangjinlaite -A New Compound Of the Ho 11 Ge 10 Typementioning

confidence: 99%

Wenjiite, Ti10(Si,P,☐)7, and kangjinlaite, Ti11(Si,P)10, new minerals in the ternary Ti-P-Si system from the Luobusa ophiolite, Tibet, China

et al. 2023

American Mineralogist

“…Sources of data for minerals not found as inclusions in corundum at Cr-11 are Xu et al (2009) and Zhang et al (2016). Sources of data for minerals found only at Cr-31 are listed here (Robinson et al, 2004;Bai et al, 2006;Yang et al, 2008;Li et al, 2009Li et al, , 2012Shi et al, 2012;Fang et al, , 2013Yang et al, 2003Yang et al, , 2015Dobrzhinetskaya et al, 2009Dobrzhinetskaya et al, , 2014. width of ∼ 4 km north-south, resulting in an exposed area of ∼ 70 km 2 (Xu et al, 2015).…”

Section: Mineral Formulamentioning

confidence: 99%

“…1, Table 1), which are located about 11 km apart in harzburgite near the contact with the transition zone dunite. Minerals separated from the Cr-31 chromitite include the ultrahigh-pressure (UHP) minerals diamond, moissanite, and coesite pseudomorphs of stishovite, as well as several new super-reduced species such as linzhiite, FeSi 2 (Li et al, 2012); titanium, Ti (Fang et al, 2013); zangboite, TiFeSi 2 (Li et al, 2009); and qingsongite (cubic BN) (Dobrzhinetskaya et al, 2009(Dobrzhinetskaya et al, , 2014. Superreduced intermetallic phases have also been found in the Cr-11 podiform chromitite orebody in the Luobusa ophiolite (Table 1, Fig.…”

Section: Introductionmentioning

confidence: 99%

“…S2a) extracted from the Cr-11 chromitite. Xu et al (2009Xu et al ( , 2013Xu et al ( , 2018 reported compounds that appear to correspond to known minerals, such as native titanium (Fang et al, 2013), Ti-Fe-Si (probably zangboite, FeTiSi 2 , Li et al, 2009), Ti-N (osbornite), and Ti-C (khamrabaevite), as well as several Ti-Si, Ti-Si-P, and Ti-B intermetallic phases.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Two new minerals, badengzhuite, TiP, and zhiqinite, TiSi<sub>2</sub>, from the Cr-11 chromitite orebody, Luobusa ophiolite, Tibet, China: is this evidence for super-reduced mantle-derived fluids?

et al. 2020

Eur. J. Mineral.

Abstract. Titanium minerals enclosed in corundum separated from the Cr-11 orebody include native Ti, zamboite (FeTiSi2), osbornite (TiN)-khamrabaevite (TiC) solid solutions, and jingsuiite (TiB2), as well as the new minerals badengzhuite (TiP) and zhiqinite (TiSi2) and two potentially new minerals, Ti11(Si,P)10 and Ti10(Si,P,□)7, where □ indicates a vacancy. These minerals together constitute a spheroid 20 µm across inferred to have crystallized from a droplet of Ti–Si–P intermetallic melt. Energy-dispersive spectroscopy and three-dimensional electron diffraction were applied to characterize the two new minerals. Badengzhuite has a primitive hexagonal cell with a=3.49(7) Å, c=11.70(23) Å, V=124(4) Å3, and crystallizes in space group P63∕mmc (Z=4). It is isostructural with synthetic TiP. Two EDX (energy dispersive X-ray spectroscopy) analyses of badengzhuite gave 60.56 wt %Ti and 39.44 wt % P and 62.74 wt % Ti and 37.26 wt % P from which an empirical formula of Ti1.020P0.980 was calculated on the basis of two atoms (ideally TiP). Zhiqinite has a primitive orthorhombic cell with a=8.18(16) Å, b=4.85(10) Å, c=8.42(17) Å, V=334(12) Å3, and crystallizes in space group Fddd (Z=8). It is isostructural with synthetic TiSi2 (C54 type). Four EDX analyses of zhiqinite gave 39.58–44.79 wt % Ti and 55.21–60.42 wt % Si, from which an empirical formula of Ti0.905Si2.095 was calculated on the basis of three atoms (ideally TiSi2). We suggest that interaction of mantle-derived CH4 + H2 fluids with basaltic magmas in the shallow lithosphere (depths of ∼ 30–100 km) under conditions more reducing than 6 log units below the oxygen fugacities corresponding to the iron–wüstite buffer resulted in precipitation of corundum that entrapped intermetallic melts, some of which crystallized to ultra-reduced Ti–P–Si phases. Experimental work on the Ti–Si and Ti–P systems indicates that the minerals enclosed in corundum could have crystallized from the alloy melt at the lowest temperature accessible on the liquidus. It has been alleged that these ultra-reduced phases are anthropogenic contaminants inadvertently introduced with fused alumina abrasive during preparation of mineral separates. Nonetheless, we conclude that the differences between the ultra-reduced minerals in the separates and the ultra-reduced phases in fused alumina are more convincing evidence for these minerals having a natural origin than the similarities between them are evidence for an anthropogenic origin.

“…Oxygen fugacities for their stability are estimated to be as much as 10 log units less than the iron-wüstite buffer (e.g., Xiong et al 2020c). Although there is no reason why these highly reduced phases could not have formed at higher pressures implied by the presence of diamond recovered from the Cr-11 orebody (Xu et al 2009(Xu et al , 2015, e.g., TiSi 2 and TiB 2 have been synthesized at pressures of 5.5 GPa or more (Li et al 2013;Zhong et al 2020), the occurrence of these phases in the Luobusa ophiolite has become increasingly controversial. Ballhaus et al (2017Ballhaus et al ( , 2018 argued that the mix of highly reduced and ultrahigh pressure minerals could be the result of lightning strikes rather than exhumation of material from deep in the mantle.…”

Section: Introductionmentioning

confidence: 99%

Jingsuiite, TiB2, a new mineral from the Cr-11 podiform chromitite orebody, Luobusa ophiolite, Tibet, China: Implications for recycling of boron

et al. 2022

American Mineralogist

The new mineral jingsuiite (TiB 2 , IMA-2018-117b), together with osbornitekhamrabaevite solid solution (TiN-TiC), deltalumite and a potential new mineral, hexagonal Ti 10 (Si,P,) 7 , constitute four inclusions up to 50 μm across in corundum recovered from the Cr-11 podiform chromitite orebody near Kangjinla, Luobusa ophiolite, Tibet, China. EELS, EDS and 3D electron diffraction were applied to study the phases. In one inclusion, jingsuiite forms a rounded grain 40 μm across. Associated osbornite-khamrabaevite solid solution forms an irregular mass up to 10 μm across having the composition Ti(N 0.5 C 0.5) and the Ti 10 (Si,P,) 7 phase forms an incomplete overgrowth up to 20 μm thick around the grain of jingsuiite. In a second inclusion, jingsuiite, osbornite-khamrabaevite solid solution, Ti 10 (Si,P,) 7 and This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.