Hello High Pressure Community:

FORCE’s next seminar will be held on Friday, Sept. 15 at noon AZ/MST (noon PT, 3 pm ET) on Zoom. Dr. Matthew Whitaker from the Mineral Physics Institute and Department of Geosciences at Stony Brook University
will give a talk titled, "Using in situ X-ray Diffraction and Imaging to Study Materials Under Pressure”. Please see the attached flyer for the talk abstract and Dr. Whitaker's bio.

Our goal is to make our seminars accessible to high pressure research experts as well as the high pressure curious. When possible, these seminars will be recorded and available for later viewing on our YouTube channel. We will hold two more seminars this semester (see schedule below).

FORCE Seminar
Fridays at noon AZ/PT

• September 15: Matthew Whitaker, Stony Brook University Zoom link
• October 20: Tim Officer, University of Chicago
• November 3: Jin Zhang: Texas A&M University

Join the FORCE mailing list here. Follow us on LinkedIn and Twitter.

Kyusei Tsuno & Kara Brugman

–––––
Kara Brugman, Ph.D. (pronunciation; s/h)
FORCE, Arizona State University
kara.brugman@asu.edu // karabrugman.com

AZ does not observe DST - check current time in AZ

Dear American Mineralogist Readers,

Below are the Paper Highlights for this month’s issue of the American Mineralogist: International Journal of Earth and Planetary Materials. You may also view the American Mineralogist Paper Highlights list at here (http://www.minsocam.org/MSA/Ammin/AM_NotableArticles.html).

The DOI links below will take you to the abstract on GeoScienceWorld.

If you have “IP” access via your institution’s library, it should reveal the whole paper. Consult your institution’s IT department or friendly librarian.

If you have MSA membership, then authenticate in from the American Mineralogist menu (herehttp://www.msapubs.org/ directly). Once at the portal page, click the right-side American Mineralogist link, enter your user name (e-mail address), and your password (membership number). Then search via your browser’s search tools for the paper you want to read. (On Rachel’s computer, it is control-f but we think that is little different for everyone.)

Note that on GSW you can sign up for a table of contents to be sent you when the issue is live -- this is a feature open to anyone who registers on the site.

Thank you for reading American Mineralogist.

Sincerely,
Hongwu Xu

Don Baker

Fluorine-rich mafic lower crust in the Southern Rocky Mountains: The role of pre-enrichment in generating fluorine-rich silicic magmas and porphyry Mo deposits

https://doi.org/10.2138/am-2022-8503

Amphiboles in the deep mafic crust of Colorado are enriched in fluorine (F). Numerical models and geochemical data support a mafic lower crustal source for F-rich shallow magmas in the region. Melts with greater mantle- or ancient felsic crustal-components lack F enrichment. The results of Rosera et al. suggest that ancient mafic lower crust in Colorado may have undergone multiple melting episodes in the Cenozoic, but F-rich magmas were only generated during periods of high heat flow that broke down F-rich amphibole.

Apatite in brachinites: Insights into thermal history and halogen evolution

https://doi.org/10.2138/am-2022-8712

Zhang et al. propose that intergranular apatite grains in brachinites have been replaced by merrillite. They find the presence of augite in pyroxene-troilite intergrowths, which are products of sulfidization of olivine. And they find that all apatite grains in brachinites have experienced chromite exsolution. They find the presence of a fluorapatite inclusion in NWA 4969 and propose that the apatite inclusions with, or without, subhedral-to-euhedral merrillite could be relicts of the precursor materials of brachinites.

A high-pressure structural transition of norsethite-type BaFe(CO3)2: Comparison with BaMg(CO3)2 and BaMn(CO3)2

https://doi.org/10.2138/am-2022-8722

This article by He et al. reported the effect of ionic radii on phase transition pressures of carbonates. The phase transition pressures of BaMg(CO3)2, BaFe(CO3)2, and BaMn(CO3)2 are 2.4(2), 2.7(5), and 3.9(2) GPa, respectively. The effective cation radii of Ba2+, Ca2+, Mn2+, Fe2+, and Mg2+ are 1.35, 1.00, 0.83, 0.78, and 0.72 Angstroms at ambient conditions, respectively. With the addition of the norsethite-type members, it is clear that a smaller metal cation tends to stabilize the trigonal structure to higher pressure in carbonates, and the phase transition pressures are much lower for norsethite-type carbonates than that of calcite- and dolomite-type carbonates. However, unlike the linear trend reported previously, the relationship tends to be nonlinear in the norsethite-type minerals. The onset of the phase transition pressures to high-pressure phases increases with cation radii for norsethite-type minerals, while the results are opposite for both calcite- and dolomite-type carbonates. This is attributed to the larger ratio between the radii of the Ba2+/(Mg2+, Mn2+, Fe2+) ions compared to that of Ca2+/(Mg2+, Mn2+, Fe2+). The effect of ionic radii on phase transition pressures has been found not only in carbonate minerals but also in other materials and can be applied to predict structural stability in isostructural materials.

An evolutionary system of mineralogy, Part VII: The evolution of the igneous minerals (>2500 Ma)

https://doi.org/10.2138/am-2022-8539

Part VII of the evolutionary system of mineralogy by Hazen et al. catalogs, analyzes, and visualizes relationships among 919 natural kinds of primary igneous minerals, which are associated with the wide range of igneous rock types through more than 4.5 billion years of Earth history. A systematic survey of the minerals in 1850 varied igneous rocks from around the world reveals that 115 of these mineral kinds are frequent major and/or accessory phases. Patterns of coexistence among these minerals, revealed by network, Louvain community detection, and agglomerative hierarchical clustering analyses, point to four major communities of igneous primary phases, corresponding in large part to different compositional regimes: (1) quartz- and/or alkali feldspar-dominant rocks, including rare-element granite pegmatites; (2) mafic/ultramafic rock series with major calcic plagioclase and/or mafic minerals; (3) rocks with major feldspathoids and/or analcime, including agpaitic rocks and their distinctive rare-element pegmatites; and (4) carbonatites and related carbonate-bearing rocks. Igneous rocks display characteristics of an evolving chemical system, with significant increases in their minerals' diversity and chemical complexity over the first two billion years of Earth history. Earth's first igneous rocks (>4.56 Ga) were ultramafic in composition with 122 different minerals, followed closely by mafic rocks that were generated in large measure by decompression melting of those ultramafic lithologies (4.6 Ga). Quartz-normative granitic rocks and their extrusive equivalents (>4.4 Ga), formed primarily by partial melting of wet basalt, were added to the mineral inventory, which reached 246 different mineral kinds. Subsequently, four groups of igneous rocks with diagnostic concentrations of rare element minerals — layered igneous intrusions, complex granite pegmatites, alkaline igneous complexes, and carbonatites — all appeared less than 3 billion years ago. These more recent varied kinds of igneous rocks hold more than 700 different minerals, 500 of which are unique to these lithologies. Network representations and heatmaps of primary igneous minerals illustrate Bowen's reaction series of igneous mineral evolution, as well as his concepts of mineral associations and antipathies. Furthermore, phase relationships and reaction series associated with the minerals of a dozen major elements, as well as minor elements, are embedded in these multi-dimensional visualizations.

Oriented secondary magnetite micro-inclusions in plagioclase from oceanic gabbro

https://doi.org/10.2138/am-2022-8784

In the paper by Bian et al., oriented needle-shaped magnetite micro-inclusions in plagioclase from oceanic gabbro occur in two generations. Primary inclusions are elongated perpendicular to seven important plagioclase lattice planes. During hydrothermal processing, they recrystallize into secondary magnetite needles aligned parallel to the plagioclase c-axis. This ensures a good match between the oxygen sublattices and a good linkage between crystal structure elements across magnetite-plagioclase boundaries.

A multi-methodological study of the bastnäsite-synchysite polysomatic series: Tips and tricks of polysome identification and the origin of syntactic intergrowths

https://doi.org/10.2138/am-2022-8678

Bastnäsite-synchysite fluorcarbonates have been investigated by several techniques, including micro-Raman spectroscopy, electron backscattered diffraction (EBSD), and high-resolution transmission electron microscopy (HRTEM) in this contribution by Conconi et al. EBSD was effective in establishing the sample orientation and to ascertain the syntactic relationship among the detected fluorcarbonates but failed to distinguish among different polysomes. Raman spectroscopy, which offers the advantage of being a non-destructive technique, allowed the distinction of different polysomes, but it could not distinguish between ordered and disordered polysomes with the same composition. HRTEM was confirmed as the ultimate technique for polysome identification, but unfortunately, it is destructive. Several ordered polysomes were detected in addition to the basic ones, including a B2S and a long-range polytype with a 32 nm repeat distance along the c-axis. Overall, the detected microstructure is indicative of a growth mechanism in which fluorcarbonates crystallize from a fluid close to thermodynamic equilibrium, whose conditions quickly and repeatedly crossed the parisite-bastnäsite stability boundary.

Petrogenesis of Chang'E-5 mare basalts: Clues from the trace elements in plagioclase

https://doi.org/10.2138/am-2022-8570

In this contribution by Tian et al., they found that (1) The melt inverted from the Chang'E-5 plagioclase has higher incompatible element concentrations than the Apollo samples but close to the KREEP-rich rocks. (2) The enrichment of trace elements reflects a high degree of fractional crystallization. (3) The parental melt’s TiO2 content estimated from the earliest crystallized plagioclase is ~3.3 wt%, suggesting a low-Ti origin for Chang'E-5 basalts.

Experimental investigation of trace element partitioning between amphibole and alkali basaltic melt: Toward a more general partitioning model with implications for amphibole fractionation at deep crustal levels

https://doi.org/10.2138/am-2022-8536

Bonechi et al. present an experimental study performed on a K-basalt at 0.8 GPa and 1030-1080 °C to provide new data on the partitioning of trace elements between amphibole and melt. Indeed, despite numerous investigations on the partitioning of trace elements between crystals and melts, there are still some mineral phases, including amphibole, for which data are limited or missing. These new data allowed them to estimate the ideal radius, the maximum partition coefficient, and the apparent Young's modulus of the A, M1-M2-M3, and M4-M4' sites of amphibole. Moreover, the influence of melt and amphibole composition, temperature, and pressure on the partition coefficients between amphiboles and glasses has also been investigated by comparing their data with a literature dataset spanning a wide range of pressures (0.6-2.5 GPa), temperatures (780-1100 °C), and compositions (from basanite to rhyolite). Finally, Bonechi et al. modeled a deep, fractional crystallization process using the amphibole-melt partition coefficients determined in this study, observing that significant amounts of amphibole crystallization (>30 wt%) well reproduce the composition of an andesitic melt similar to that of the calc-alkaline volcanic products found in Parete and Castelvolturno bore-holes (NW of Campi Flegrei, Italy).

Grain-scale zircon Hf isotope heterogeneity inherited from sediment-metasomatized mantle: Geochemical and Nd-Hf-Pb-O isotopic constrains on Early Cretaceous intrusions in central Lhasa Terrane, Tibetan Plateau

https://doi.org/10.2138/am-2022-8508

Combined zircon U-Pb, Hf, and O isotope investigations are widely used to address the contribution of mantle and sediment components in the source of igneous rocks. In particular, zircon Hf isotopic variabilities in a single sample beyond the analytical uncertainty are commonly interpreted as the mixing of magmas derived from two isotopically different reservoirs. However, subducted sediments may have profound impacts on the Hf budget of the mantle, theoretically adding complexity to interpreting zircon Hf data. Nevertheless, compared with granitoids, Hf isotopic variation is rarely observed in zircons of mafic rocks. In this study, Li et al. report integrated data of whole-rock geochemistry (major, trace elements, and Sr-Nd isotopes), zircon U-Pb, Hf and O isotopes and trace elements, and in situ clinopyroxene major and trace elements and Pb isotopes, for some newly recognized gabbro-diorite rocks in central Lhasa Terrane, Tibetan Plateau. The magmatic zircons present dramatically heterogeneous Hf isotopes (from +13 to -4) even in the same individual grain, yet their O isotopes are relatively uniform and are slightly higher than that of the mantle value. Combined with their relatively constant clinopyroxene Pb isotopes and whole-rock geochemistry, they contend that the zircon Hf isotope heterogeneities were inherited from a depleted asthenospheric mantle metasomatized by 1-4% terrestrial sediments. Their study, therefore, emphasizes caution when using zircon Hf isotopes as arguments of involvement of two end-member magmas at the crustal level without comprehensive mineral and geochemical investigations.

Mechanism and kinetics of the pseudomorphic replacement of anhydrite by calcium phosphate phases at hydrothermal conditions

https://doi.org/10.2138/am-2022-8592

This study by Roza-Llera et al. focuses on the kinetics of the replacement of anhydrite single crystals by mixtures of the calcium phosphate phases, beta-tricalcium phosphate, and hydroxyapatite via an interface-coupled dissolution-precipitation reaction in the temperature range between 120 to 200 °C. Both the Avrami and the iso-conversion methods yield an empirical activation energy Ea (kJ/mol) of about 40 kJ/mol for this replacement reaction. The dissolution of anhydrite appears to be the rate-limiting process, and the overall kinetics of the replacement reaction is controlled by the rate of diffusion of dissolved species through the pore network. These results open a window for the development of new strategies for the recovery of P, a scarce element in the Earth's crust, through the precipitation of phosphate phases through dissolution-crystallization reactions that involve a pre-existing mineral.

Vacancy infilling during the crystallization of Fe-deficient hematite: An in situ synchrotron X-ray diffraction study of non-classical crystal growth

https://doi.org/10.2138/am-2022-8379

The work by Chen et al. highlights a non-classical crystallization pathway involving vacancy infilling by cations during nanoparticle growth. Incipient hematite nanocrystals nucleated with Fe deficient concentrations as high as 40 mol%, and the Fe occupancy increased as Fe3+ cations replaced H+ during crystal growth until reaching a steady state. The steady-state vacancy concentration in the final product could be controlled by the reaction environment, including pH, temperature, and time.

Simulated diagenesis of the iron-silica precipitates in banded iron formations

https://doi.org/10.2138/am-2022-8758

Iron-silica precipitates were once deposited across the ocean, but the legacy of this time now only lives on in iron and silica-rich minerals hosted in rocks known as Banded Iron Formations (BIFs). Hinz et al. developed a new experimental method to partially oxidize iron under ancient ocean-like conditions and initially formed a precursor iron silicate, similar to the mineral greenalite recently proposed as the original BIF sediment, as well as subsidiary iron oxides. After simulated post-depositional aging, they observed crystallization of Mg-rich greenalite and magnetite, a common BIF mineral, as well as some persistent iron oxides, suggesting new ways to identify alteration and extract primary information held in BIFs.

Wave vector and field vector orientation dependence of Fe K pre-edge X-ray absorption features in clinopyroxenes

https://doi.org/10.2138/am-2022-8547

The pre-edge energy range of X-ray absorption spectra is commonly used to quantify redox ratios of multivalent elements. In contrast with anisotropy observed as optical pleochroism in petrographic thin sections, pre-edge absorption is largely the product of quadrupole transitions. With this difference in mind, Steven et al. find that in different analytical geometries, the absorption anisotropy is as much a function of the propagation direction as is the polarization direction for the pre-edge absorption of clinopyroxenes.

Structure and compressibility of Fe-bearing Al-phase D

https://doi.org/10.2138/am-2022-8559

Criniti et al. studied the crystal structure and compressibility of Fe-bearing Al-phase D, a possible major water carrier in Earth's mantle transition zone and shallow lower mantle. They found that the symmetry and crystal structure of this phase are intermediate between those of pure Mg-phase D and Al-phase D, while its bulk modulus is in agreement with some previous studies on Mg-phase D. Additionally, no change in the compression behavior due to the symmetrization of H-bonds was found, suggesting the elasticity of phase D is relatively insensitive to the chemical composition and degree of order.

Synthesis of boehmite-type GaOOH: A new polymorph of Ga oxyhydroxide and geochemical implications

https://doi.org/10.2138/am-2022-8568

A new polymorph of GaOOH (γ-GaOOH) was synthesized with boehmite as a structure template. The results provide insight into Ga in boehmite and indicate that boehmite can act as a template to enrich free Ga and epitaxially induce nucleation and growth of γ-GaOOH. This study by Liu et al. also provides a potential migration, enrichment, and mineralization mechanism of Ga, which will improve the understanding of the geochemical processes and occurrence of Ga in nature.

Scheelite U-Pb geochronology and trace element geochemistry fingerprint W mineralization in the giant Zhuxi W deposit, South China

https://doi.org/10.2138/am-2022-8495

Skarn-type tungsten deposits dominate the world's W supply, however, the temporal relation between the W mineralization, causative intrusions, and the sources of ore-forming fluids and metals is still a matter of great debate. In this contribution, Zhao et al. report in situ LA-ICP-MS U-Pb dating and trace element compositions of scheelite from the world's largest tungsten deposit to address the above issues. Their study highlights that, compared to other hydrothermal accessory minerals (such as molybdenite, muscovite, apatite, etc.), scheelite LA-ICP-MS U-Pb dating is a robust technique to determine the mineralization age of skarn W deposits. This study also discovered that the destruction of early-formed garnet could produce a high Y/Ho ratio for the subsequent ore-forming fluid and could provide metals such as W, Cu, and Sn to form skarn-type ore deposits. The new results from this study contribute to a better understanding of the metal source and fluid evolution for the skarn-type ore deposits.

A rare sekaninaite occurrence in the Nenana Coal Basin, Alaska Range, Alaska

https://doi.org/10.2138/am-2022-8698

In this contribution by Reidel and Ross, coal-seam fires represent an unusual and relatively unexplored natural environment of mineral formation in pyrometamorphic rocks. The Mystic Creek coals burned with an extremely high temperature and produced sekaninaite, a relatively rare mineral as well as a yet unidentified Al-Fe-TI opaque mineral. This coal-seam fire is a natural laboratory for observing low-pressure, high-temperature fractional crystallization paths in magmas. Thus, pyrometamorphic rocks like that at the Mystic Creek coal basin provide a valuable natural laboratory for exploring magmatic processes and new minerals for future mineralogical studies.

Slyudyankaite, a new sodalite-group mineral from the Malo-Bystrinskoe lazurite deposit, Baikal Lake area

https://doi.org/10.2138/am-2022-8598

The article by Sapozhnikov et al. is a contribution to the crystal chemistry of sodalite-group minerals. It describes the new mineral slyudyankaite, approved by the IMA CNMNC. Slyudyankaite is a very unusual new member of the sodalite group containing S6 and CO2 molecules as species-defining components. This mineral is an example of the separation of extra-framework components in cages of two types. Cages of the first type contain cations (Na+ and Ca2+) and SO42- anions, whereas cages of the second type are occupied by neutral molecules (S6, S4, CO2, and H2O). Based on a multimethodic approach involving six spectroscopic methods, it was shown that the variable color of slyudyankaite is related to the presence of polysulfide chromophores (S6 molecules as well as trace amounts of S2-, S3-,·and S4·;- radical anions). Extra-framework components in slyudyankaite and other sodalite-group minerals are important markers of volatile species in the mineral-forming medium.

Ruizhongite, a thiogermanate mineral from the Wusihe Pb-Zn deposit, Sichuan Province, Southwest China

https://doi.org/10.2138/am-2023-9000

The discovery of ruizhongite has significant implications for the occurrence and enrichment mechanism of Ge in sphalerite and other metallic minerals. Ruizhongite, a thiogermanate mineral, was identified in the Wusihe Pb-Zn deposit in Sichuan Province, Southwest China, during an investigation of the mineralogy of this deposit. In the present study by Meng et al., polarized optical microscopy, scanning electron microscopy, electron microprobe, μ-X-ray diffraction, and Raman spectroscopy analyses were utilized to characterize the occurrence, optical property, chemical composition, and crystal structure of ruizhongite. Both the mineral and its name have been approved by the IMA-CNMNC (2022-066). Type specimens are preserved in the Geological Museum of China, Beijing, China (Catalog number M16138).