Abstract The Earth has shown a systematic increase in mineral species through its history, with three ‘eras’ comprising ten ‘stages’ identified by Robert Hazen and his colleagues ( Hazen et al. 2008 ), the eras being associated with planetary accretion, crust and mantle reworking and the influence of life, successively. We suggest that a further level in this form of evolution has now taken place of at least ‘stage’ level, where humans have engineered a large and extensive suite of novel, albeit not formally recognized minerals, some of which will leave a geologically significant signal in strata forming today. These include the great majority of metals (that are not found natively), tungsten carbide, boron nitride, novel garnets and many others. A further stratigraphic signal is of minerals that are rare in pre-industrial geology, but are now common at the surface, including mullite (in fired bricks and ceramics), ettringite, hillebrandite and portlandite (in cement and concrete) and ‘mineraloids’ (novel in detail) such as anthropogenic glass. These have become much more common at the Earth’s surface since the mid-twentieth century. However, the scale and extent of this new phase of mineral evolution, which represents part of the widespread changes associated with the proposed Anthropocene Epoch, remains uncharted. The International Mineralogical Association (IMA) list of officially accepted minerals explicitly excludes synthetic minerals, and no general inventory of these exists. We propose that the growing geological and societal significance of this phenomenon is now great enough for human-made minerals to be formally listed and catalogued by the IMA, perhaps in conjunction with materials science societies. Such an inventory would enable this phenomenon to be placed more effectively within the context of the 4.6 billion year history of the Earth, and would help characterize the strata of the Anthropocene.

Abstract In this chapter, we describe the hydrothermal diamond-anvil cell (HDAC), which is specifically designed for experiments on systems with aqueous fluids to temperatures up to ~1000°C and pressures up to a few GPa to tens of GPa. This cell permits optical observation of the sample and the in situ determination of properties by ‘photon-in – photon-out’ techniques such as Raman spectroscopy. Several methods for pressure measurement are discussed in detail including the Raman spectroscopic pressure sensors α-quartz, berlinite, zircon, cubic boron nitride ( c -BN), and 13 C-diamond, the fluorescence sensors ruby , Sm:YAG and SrB 4 O 7 :Sm 2+ , and measurements of phase-transition temperatures. Furthermore, we give an overview of published Raman spectroscopic studies of geological fluids to high pressures and temperatures, in which diamond anvil cells were applied.

We present a new technique for X-ray microtomography under high pressure. By modifying an opposed-anvil high-pressure cell known as the Drickamer cell, monochromatic X-ray radiographs can be collected through the entire cell assembly and a thin-walled containment ring. We designed a rotation mechanism to rotate the Drickamer cell from 0 to 180° under hydraulic load, and examined pressure-generation efficiencies of the Drickamer cell up to 8 GPa at room temperature using the energy-dispersive technique through the containment ring, which allowed us to conduct a detailed evaluation of effects of geometric factors of the Drickamer anvils for tomography application. The maximum attainable load supported by the containment ring is proportional to the anvil diameter. Cells with larger anvil diameters are less pressure efficient, although they can reach higher pressures with much higher loads. Pressure efficiency generally increases with the tapering angle and decreases with tip diameter of the anvils. However, cells with larger tapering angles are more unstable, causing blowouts beyond a certain pressure. We evaluated the quality of X-ray images using the optical setup for conventional tomography at the GSECARS (GeoSoilEnviroCARS [Consortium for Advanced Radiation Sources]) beam line, the Advanced Photon Source. Noise level in the images depends on the material used for the containment ring. Containment rings made of either cubic boron nitride or silicon carbide allow us to better observe the images, but these materials are brittle and prone to mode-1 failure and are not suitable for high-pressure generation. The noise level of aluminum-alloy rings is somewhat higher, but the material is much more ductile, and hence it is capable of supporting higher loads. Using the aluminum-alloy containment ring, we conducted a commissioning run of tomography up to 3 GPa. We demonstrate that the high-pressure tomography setup is useful for studying internal structure of objects and density of melt and fluid under pressure.