Stanford Magnets’ Post

Coming in hot... (about 300 degrees C) Join us in Ballarat for perhaps the last GPIC of the year! ...and what a speaker we have lined up! Dr Chris Voisey will be presenting on his groundbreaking research on the piezoelectricity of quartz as a result of earthquakes. Why does this matter? It is on how gold nuggets form! To register: https://lnkd.in/gv7Yn52F Central Victoria Branch December tech talk: GPIC Ballarat – Chris Voisey on “Gold accumulation driven by earthquake-induced piezoelectricity” For thousands of years people have observed that coarse gold occurs almost exclusively in quartz veins, as either large nuggets or as highly interconnected fracture networks. The current understanding is that gold is precipitated together with quartz from hydrothermal fluids in response to changes in temperature, pressure, and/or fluid chemistry. The overall mechanisms that are responsible for the transport and deposition of gold are relatively well understood, resulting from an interplay between these geochemical and structural factors. However, no widely accepted mechanism can explain the extreme localisation of gold needed to form large nuggets that occur in orogenic quartz veins. They represent a long-unsolved paradox: the solubility of gold in fluids is up to ~1 ppm, whereas the local concentration of gold in quartz can even exceed 50%. Here, we investigate whether piezoelectric discharge from quartz crystals during earthquakes can provide a suitable explanation for extreme gold localisation in orogenic quartz veins. Quartz is the only abundant piezoelectric mineral on Earth, meaning that when distorted under stress the crystals produce an electrical potential proportional to the applied force. Seismic activity that drives orogenic gold deposit formation means that quartz crystals in veins will experience thousands of episodes of deviatoric stress. The elastic rattling of quartz during this activity creates an oscillating piezoelectric voltage that induces alternating oxidation-reduction reaction fronts on crystal surfaces. When this voltage shifts the energy of the quartz valence band above the redox potential of Au-bearing ligands, gold will be electrochemically deposited. Venue : The George Hotel, 27 Lydiard St North, Ballarat Central VIC 3350 Date : Tuesday, 10 December 2024 Time : 5.30pm – 8.30pm

Crystallization Instability in Glass-Forming Mixtures https://lnkd.in/dkbxE-ZZ Most materials are mixtures, and their behavior is usually very different from that of their parts in isolation. Amorphous metal mixtures, so-called metallic glasses, promise materials with extreme toughness and strength. However, spontaneous separation of the constituents destroys the benefits of the mixture, and results in crystallization in amorphous materials. This separation is vital not solely in synthetic glasses but also in volcanoes, where crystallization of the magma has profound consequences for its flow properties and might result in catastrophic volcanic explosions. Here, we reveal a universal mechanism for crystallization in mixtures, and we show that when the individual components without delay crystallize, which is nearly always the case, the mixture is vulnerable to crystallization. Crystallization in super cooled liquids has profound implications in fields as diverse as the development of amorphous materials, magma flows in volcanos, and aqueous solutions of ions. Materials in question include metallic, inorganic, and chalcogenide glass formers, where mixtures of a number of different constituents have the effect of suppressing or controlling crystallization [4]. Alas, this tendency to crystallize places stringent limits on the size of the pieces of amorphous material that can be formed: large pieces are more likely to undergo crystal nucleation. This “Achilles heel” of glass formation thus limits the exploitation of metallic glasses, for example, whose superior mechanical properties otherwise hold great promise.

A recent Forbes article highlights an exciting new discovery that builds on quartz's unique properties—specifically its piezoelectric effect. Researchers have found that quartz, when stressed by seismic activity, can accumulate gold over time, acting like a natural battery. This process not only underscores quartz’s remarkable role in mineral transformations but also aligns with the article I posted last night on its adsorption capacity in desert soils in 'Greening Desert - 1.3 - Deserts and the Cosmos'. https://lnkd.in/dakUzR8a

Is lunar dust an issue for you? Philipp Zanon and myself are developing a solution! As part of experimentally validated tests in a dusty thermal vacuum chamber, we want to refine our work towards a powerful software package that can predict dust loading behaviour. To maximize the impact we can make, we want to understand your problem better. We'd love to hear about how we can tailer this solution to the broader ISRU and terrestrial mining community. If you have any questions or want a deeper conversation feel free to contact us directly on LinkedIn

Struggling with dust? Whether it’s terrestrial or extra-terrestrial, we want your insights! Daniel Ricardo and I are in the processes of validating a spin out company using IP developed from our moon-based Ph.D. topics. Through this work I created a dust simulation model that was validated in a dusty thermal vacuum chamber we built together.  We intend to refine our work into a powerful tool that predicts and simulates dust behavior on the Lunar surface and within the mining sector. We have created a brief and anonymous questionnaire to explore the business case for a dust mitigation product or service. If you have the time or want to interrupt your doom scroll, please take the time to fill out this survey. We would love to hear from the terrestrial and extra-terrestrial community to aid us in building a bespoke solution. Your feedback will help inform the direction of our efforts to demystify dust, allowing for a preventative approach to dust mitigation on Earth and in space. Thanks in advance! 😊 Feel free to contact us with any questions or want to learn more about our work. #dustmitigation #dust #Australianspace #mining #space #lunar #lunardust

formation of gold nuggets. We find that stress on quartz crystals can generate enough voltage to electrochemically deposit aqueous gold from solution as well as accumulate gold nanoparticles. Nucleation of gold via piezo-driven reactions is rate-limiting because quartz is an insulator; however, since gold is a conductor, our results show that existing gold grains are the focus of ongoing growth. We suggest this mechanism can help explain the creation of large nuggets and the commonly observed highly interconnected gold networks within quartz vein fractures. https://lnkd.in/dwmieUrG

Anionic and Magnetic Ordering in Rare Earth Tantalum Oxynitrides with an n = 1 Ruddlesden–Popper Structure Rare earth tantalum oxynitrides are investigated in this article, focusing in the geometry of these newly synthetised compounds. https://bit.ly/3x0j7DB

Carbonatites are truly fascinating magmatic rocks! Their compositions are so unusual, including the fact that some of these rocks host significant rare earth element (REE) deposits. Despite the extensive research conducted in recent years, our comprehension of their genesis and the composition of initial carbonatite melts is constrained by two significant obstacles: the majority of carbonatites observed are intrusive rocks, and they are frequently affected by metasomatic overprint! In this study, our team presents experimental data in which apatite is used as a geochemical proxy to investigate the composition of carbonatite melts by tracing the evolution of these rocks through crystallisation and metasomatic events. https://lnkd.in/e3JNPZQQ #CriticalMinerals #RareEarthElements #Carbonatite #Apatite