Mineralogical Society of America

American Mineralogist:
Deciphering the origin of low-grade W mineralization and hydrothermal fluids in the oxidized Fujiashan W skarn deposit using garnet geochemistry
Guiqing Xie, Yunhao Ji, Simon Jowitt, Denis Fougerouse, Wei Li, Bin Fu
https://doi.org/10.2138/am-2024-9452
Garnet plays a crucial role in skarn deposits, with its chemical and isotopic composition serving as valuable indicators for understanding the origin and evolution of mineralizing fluids. Fluorine potentially facilitated the transportation of Al to the distal skarn in this deposit, leading to an elevation in the grossular component from the proximal to distal skarn zones. These variations suggest that the zoning patterns within W skarn systems may differ from those observed in other types of skarn systems, such as Cu skarns. This study highlights high concentrations of W within andradite and lacks evidence of re-equilibration during retrograde alteration. This suggests W within W-rich garnet is unlikely to be remobilized by fluids and reconcentrated as scheelite. This may explain the low W grade in oxidized skarns.

American Mineralogist:
A first-principles investigation on the enthalpy landscape for the hibonite solid solution: Implications for a nebular barometer
Pierre-marie Zanetta, Abhishek Thakur, Venkat Manga, Krishna Muralidharan, Thomas Zega
https://doi.org/10.2138/am-2024-9449
The abundance of titanium (Ti) in hibonite, a mineral forming very early in solar nebula condensation, can be important to understanding the chemical environment of this system. In part, the Ti content reflects fO2 of the equilibrating environment, considering the variable oxidation states of the element (Ti3+ and Ti4+). However, bulk composition of the system also mitigates the valence state of Ti in hibonite. Zanetta and coauthors applied density functional theory to known hibonite compositions to determine that coupled substitution (Ti4++Mg2+ for 2Al3+) was the most energetically favorable mechanism for Ti incorporation. The research is an important step toward comprehensive thermodynamic modeling of early solar system materials.

July American Mineralogist:
Kyanite-muscovite-dumortierite vein mineralization mechanisms from advanced microstructural analysis using EBSD
Sneha Dandekar, Elisabetta Mariani, Tushar R. Dandekar, Rajesh Khatirkar, Kavita Pande, Joseph Gardner, Heath Bagshaw, Kirtikumar Randive, Dilip Peshwe
https://doi.org/10.2138/am-2024-9380
This is the first comprehensive microstructural EBSD study of dumortierite, an aluminous silicate containing boron, a critical element for the energy transition. Dumortierite crystallizes from reactive fluids transported by transient porosity waves generated along muscovite basal surfaces by new defects known as ripplocations. This mineralization mechanism has important implications for understanding the occurrence and distribution of dumortierite in muscovite-rich rocks.

The Journal of Gemmology
The latest edition of The Journal of Gemmology is now available (Volume 39, Number 6). Articles include, among others: "A New Discovery of Common Opal from Antetezambato, North-western Madagascar" and "New Insights into the Factors influencing the UV Fluorescence and Colour of Red Spinel from Myanmar."

Volume 39/ Issue 6/ 2025 | Gem-A Volume 39/ Issue 6/ 2025 | Read this issue of the Gem-A Journal of Gemmology. Download the PDF and explore related issues.

Thin Section Thursday!
Schist from the Ivrea-Verbano zone, northern Italy, showing end-sections of sillimanite, with moderate relief, square to rectangular cross-sections, and inclined cleavages running corner-to-corner. Other minerals are high relief, honey-brown rutile, low relief colorless plagioclase and quartz, and a big grain of high relief, colorless garnet, a little south of the center. In crossed-polars, the sillimanite is gray because you’re looking at end sections. The garnet is black, and the plagioclase and quartz are gray to white. Only the rutile and alteration of feldspars shows high interference colors. Field of view: 2 mm. Contributed by Matt Kohn.
You can contribute too! Send images and a caption to akoziol1 at udayton dot edu.

Upcoming Meetings
MSA's Inaugural Symposium in Tucson, AZ: MSA will be hosting its Inaugural Symposium on February 16-18, 2026 in Tucson, Arizona. There will be field trips in the area on Monday, February 16, followed by two days of talks. The venue is The Pima County Historic Courthouse in downtown Tucson, which is also the home of The University of Arizona's Alfie Norville Gem & Mineral Museum. The symposium dates were chosen as they immediately follow the Tucson Gem & Mineral Show housed in the Tucson Convention Center. Please put the dates on your calendar. A message will go out to MSA Members when the call for abstracts is open.

Geological Society of America's Annual Meeting: MSA will have its usual events at the Annual Meeting of the Geological Society of America, which takes place this year in San Antonio, TX, October 19-22, 2025.

This year, GSA is offering a 15% discount on conference registration to members of its Associated Societies. To receive the discount, use code 25CONNECTS_MSA during the registration process.

MSA's events include the MSA Awards Luncheon at noon on Tuesday, October 21, followed by the Awards Lectures and Presidential Address from 3 - 5 PM that same day. There are also a number of MSA-sponsored sessions on the program (abstract submission deadline is August 5, 2025). MSA will have a booth in the Exhibit Hall, so please stop by and say hello.

Send a message to learn more

American Mineralogist:
Progressive change in dislocation microstructures in shocked calcite with pressure: Characterization of micrometeoroid bombardment on asteroid Ryugu
Naotaka Tomioka, Kosuke Kurosawa, Akira Miyake, Yohei Igami, Takayoshi Nagaya, Takaaki Noguchi, Toru Matsumoto, Masaaki Miyahara, and Yusuke Seto
https://doi.org/10.2138/am-2024-9540
The progressive change in the dislocation microstructure of experimentally shocked calcite was studied by transmission electron microscopy. The calcite shows a drastic increase in dislocation density: dislocation nucleation occurs heterogeneously on the slip planes at ~3-6 GPa and homogeneously throughout the crystal above 6 GPa. The microstructural changes are suitable for new efficient pressure barometers for weakly shocked hydrated planetary materials, represented by the regolith particles of the asteroid Ryugu.

Progressive change in dislocation microstructures in shocked calcite with pressure: Characterization of micrometeoroid bombardment on asteroid Ryugu | American Mineralogist | GeoScienceWorld Abstract. Shock recovery experiments were performed using a two-stage light gas gun to clarify the progressive deformation microstructures of calcite at

Mineral Monday!
Micrometeorites are HOT!
by Gottlob
Micrometeorites (=MM) originate from asteroids, comets or interstellar sources. They allow us to study cosmic material, offer us insights into their formation and provide proof of the chemical and mineralogical diversity within the solar system.
Two 2025 articles give you a flavor of “what’s hot in the mineral kingdom”:
Unique (Al,Cu)-alloys discovered in a MM from Italy (April)
An aluminum-copper (Al,Cu)-bearing MM was found at the top of Mt. Gariglione. It exhibits a highly vesicular scoriaceous structure characterized by broadly chondritic silicate-dominated composition (S-type) with relict phenocrystals of forsteritic olivine dispersed in a Ca-rich silicate glass with pyroxene composition, droplets of FeNi metal, oxides and sporadic Ni-rich sulphides embedded in a magnetite rim. A reduced assemblage of (Al,Cu)-alloys partially fills the open voids of the MM and shows variable compositions: from almost pure Cu up to Al-dominated phases with a predominance of khatyrkite, stolperite and unnamed Cu3Al2. Locally, 1-2 µm grains embedded in stolperite show a Fe-Si enrichment and are characterized by a long-range ordering resembling a quasicrystalline structure, representing a unique natural quasicrystal approximant with composition Al52Cu31Fe10Si7.
Rare (Al,Cu)-bearing MM from the Project Stardust collection (June)
We report the discovery of (Al,Cu)-bearing metallic alloys in two MM found in the Project Stardust collection gathered from urban rooftop environments in Norway. Most of the alloys are the same as those found in the Khatyrka meteorite and other MM, though one has a composition that has not been reported previously. Oxygen isotope ratio measurements using secondary ion mass spectrometry show that the Project Stardust samples reported here, like all earlier examples of natural (Al,Cu)-bearing alloys, contain material of chondritic affinity.
So far 5 objects have been found containing (Al-Cu) alloys. What was once regarded as an anomaly, now seems to be part of a most intriguing phenomenon, thanks to … micrometeorites! And the best news: you can collect them too!!

American Mineralogist:
Ezochiite and shiranuiite are cuprorhodsite and are not new mineral species
Louis J. Cabri and Andrew M. McDonald
https://doi.org/10.2138/am-2024-9517
Cabri and McDonald examined the data for the new mineral species ezochiite and shiranuiite and argued that they are not new unique minerals but rather represent varieties of cuprorhodsite, ideally CuRh2S4.

Ezochiite and shiranuiite are cuprorhodsite and are not new mineral species | American Mineralogist | GeoScienceWorld Abstract. Ezochiite was described as a newly discovered platinum-group mineral in the thiospinel group having an ideal formula of Cu+(Rh3+Pt4+)S4

You are invited to the next Zoom webinar:
Mineral Talks LIVE
2 July 2025 1:00 PM Eastern Time (US and Canada)
Speaker: Gerhard Wagner

Register: http://go.mineraltalkslive.com/register

After registering, you will receive a confirmation email containing information about joining the webinar.

Gerhard Wagner’s lifelong passion for minerals began with a childhood discovery of a fossil on the shores of Lake Constance. That moment sparked a fascination that grew into a world-class collection, culminating in the landmark Gerhard Wagner Collection of Fine Mineral Specimens, showcased in The World of Tourmaline and auctioned by Heritage Auctions in June 2015.
As a young man, Gerhard honed his collecting skills with field trips and guidance from mentors, particularly a Black Forest dealer named Stempel. His early career in the toy industry funded his hobby, and by his 30’s, Wagner had become a serious mineral collector. His focus eventually narrowed to tourmaline, captivated by its stunning diversity of colors and forms.
Today, retired and ever-curious, Wagner continues to roam mineral shows and mine sites worldwide, the thrill of discovery still vivid. His journey reflects not just a collector’s eye—but a lifetime of curiosity, discipline, and passion.

American Mineralogist:
Influence of cation disorder on the mineral physics of ankerite
Azzurra Zucchini, Tiziana Boffa Ballaran, Maximiliano Fastelli, Davide Comboni, Michael Hanfland, Francesco Frondini, and Paola Comodi
https://doi.org/10.2138/am-2024-9495
The structural evolution and compressibility of ordered and disordered ankerite at pressures up to ~25 GPa were studied using synchrotron single crystal X-ray diffraction in diamond anvil cell. Ordered ankerite (space group R3) undergoes discontinuous phase transition between 12.15 and 13.45 GPa to a high-pressure structure called ankerite-II (space group P1) that has Ca in eight-fold coordination. Disordered ankerite (R3c space group) does not undergo a phase transition in the investigated pressure range. The results provide the basis for further studies of the influence of ankerite on the low-velocity anomalies observed in the mantle wedge.

Influence of cation disorder on the mineral physics of ankerite | American Mineralogist | GeoScienceWorld Abstract. The structural evolution and compressibility of ordered and disordered ankerite were investigated at pressures up to ∼25 GPa using synchrotron

Thin Section Thursday!
Another kinzigite from the Ivrea-Verbano zone, northern Italy. This kinzigite has relatively little biotite, but it is characteristically red-orange in plane-polarized light. Some dark, honey-brown, rutile is scattered throughout, but only the large grains in the NE area of the slide are large enough to see the color. High relief makes the others look black. Abundant prismatic sillimanite runs approximately E-W across the field of view. In crossed polars, deformation bands are evident in alternating dark and light areas running approximately N-W (i.e., perpendicular to the prisms). Garnet is characteristically high relief in plane-polarized light and black in crossed polars. There’s a little quartz and plagioclase, also. Field of view: 5 mm across. Contributed by Matt Kohn.