The 1922 Rand Rebellion was the only instance of worker protest in the twentieth century in which a modern state used tanks and military airplanes, as well as mounted infantry, to suppress striking workers. These circumstances were unprecedented in their own time and for most of the century. The compressed and intensely violent rebellion of twenty thousand white mineworkers in South Africa’s gold mines had several overlapping features. Within a matter of days—from 6 to 12 March—it went from a general strike to a racial pogrom and insurrection against the government of Prime Minister Jan Smuts. Throughout all these twists and turns, the battle standard remained, “Workers of the world unite and fight for a White South Africa!” Race and violence were integral features of South Africa’s industrial history, but they do not explain the moments when discrete groups of people chose to use them as weapons or bargaining tools. At the close of the First World War, for instance, South Africa’s white mine workers demanded a more comprehensive distribution of the privileges of white supremacy, but in a manner that was both violent and contentious. Consequently, South Africa’s immediate postwar period became one of the most violent moments in its history.

Phyllosilicate mineralogy is key to understanding hydrothermal processes within accepted epithermal deposit models but little information has been published about the mineral chemistry of epithermal deposits. X-ray diffraction, optical and electronic microscopy (scanning and transmitted), electron microprobe, and Fourier transform infrared spectroscopy were used in this work to study phyllosilicates in the Palai-Islica Au-Cu epithermal, volcanic-hosted deposit, in order to link phyllosilicate mineralogy and mineral chemistry to ore genesis. Different phyllosilicate assemblages are characteristic of two types of mineralization, and related hydrothermal alteration. Chlorite and mica appear in polymetallic quartz veins with sulfides, and in the related chloritic and sericitic hydrothermal alteration. These minerals have notable textural and chemical differences (i.e. Fe/(Fe+Mg), Si and Al in chlorite and illitic and phengitic components in mica) amongst veins and altered rocks, revealing different genetic conditions. These chemical features also distinguish propylitic and regional, non ore-related, low-temperature alteration. Hot hydrothermal fluids of near-neutral pH are responsible for vein mineralization and alteration. Illite, interstratified illite-smectite, kaolinite, and pyrophyllite are characteristic, with a distribution pattern by zones, of the intermediate argillic and advanced argillic alteration around areas of silicification. In the latter, native gold appears associated with interstratified illite-smectite, suggesting a relatively low-temperature formation. Hot, low-pH fluids are responsible for this mineralization and alteration assemblage. The present study contributes to epithermal models showing the co-existence of two different alteration styles in the same hydrothermal system.

TheAu-Cu (±Pb, Zn, Ag) prospects of Lavras do Sul, southernmost Brazil, arehosted in Neoproterozoic granitic and volcanogenic rocks. Mineralization occurs in structurally controlled N40°W to E-W quartz veins; sericite (±chlorite) and sulfides are the main secondary minerals in associated wall rocks.

In the present contribution we use petrography (optical microscopy and scanning electron microscopy (SEM)), mineralogy (X-ray diffraction (XRD) with polytypes, FWHM, decomposition of diffraction patterns), and crystal chemistry of samples from several prospects to document the spatial and temporal evolution of sericitic alteration of veins and wall rocks associated with gold.

Hexagonal, coarse-grained 2M1 phengite-rich alteration (± illite) is best developed with coarse-grained primary growth (comb) quartz + pyrite ± Au veins and altered wall rock from the western portion of the granitic complex (phyllic alteration). Pure phengite was recognized by narrow XRD profiles (FWHM ⩽ 0.2°2θ CuKα) of the <5 µm particle-size fraction, non-expandable d001 X-ray reflections and interlayer charge (IC) >0.9 per O10(OH)2.

Towards the eastern zones of the granitic complex and in the volcanogenic rocks, wider XRD profiles (FWHM values ⩾ 0.2°2θ CuKα) were decomposed. They contain mixtures of coarse- to fine-grained, lath-like crystals of both 2M1 and 1M illite (non-expandable d001 X-ray reflections, IC between 0.85 and 0.89 per O10(OH)2) with expandable d001 reflections associated with lath-like, fine-grained crystals of ordered (R ⩾ 1) illite-rich I-S (80–90% of illite; IC of ∼0.8 per O10(OH)2), and minor amounts of regularly ordered (R = 1), illite-rich I-S mixed layers (75% of illite; IC of ∼0.74 per O10(OH)2). The dioctahedral clay association of illite + illite-rich I-S mixed layers (intermediate argillic alteration) is best developed in quartz + pyrite ± Au veins, breccias, and wall-rock alteration from the eastern portion of the granitic complex and in the volcanic area. Quartz from veins and breccias has fine-grained primary growth, recrystallization, and replacement textures, similar to those in epithermal deposits.

The overall distribution of the dioctahedral clays indicates that the study area represents a fracture-controlled, tilted, porphyry to epithermal deposit, with telescoping alteration features observed in the east of the mining district. Deeper levels of exposure of a large hydrothermal system are observed in the west of the mining district, as shown by higher-rank dioctahedral minerals (phengite) that crystallize at relatively high temperatures (Tphe ≈ 300°C, phyllic alteration) associated with coarse-grained, primary-growth quartz veins, similar to those observed in porphyry deposits. On the other hand, shallower levels of exposure are observed in the east of the study area, associated with abundant, lower-rank dioctahedral clay minerals (illite + illite-rich I-S mixed layers, intermediate argillic alteration) that crystallize at relatively lower temperatures (TI-S ≈ 120–200°C).

Available data show that gold is associated with phengite, but that lower-rank, overprinting alteration characterized by illite-I-S may have locally modified the original gold grades.

The Shahnamah (RAS 239) copied for the Timurid prince, Muhammad Juki (1402–1445) in Herat, has long been considered one of the finest surviving, illustrated Timurid manuscripts. It was presented to the RAS in 1834 by Lieutenant Colonel Doyle (1787–1848), but attracted little scholarly attention until Barbara Brend published her monograph in 2010. The manuscript contains 31 exquisite miniature paintings, two of which (fol. 430v and fol. 531r) were added later during the Mughal period (1526–1761). This article will examine the sumptuous, jewel-like colours employed to depict scenes from the epic and the metals, pigments, and dyes from which they were derived. Precious metals and organic colours made from plants such as indigo and lac extracted from female insects are examined in detail: the methods of their production and extraction, the techniques used for their application, their commercial value, and the prestige they afforded their patrons all contribute to an understanding of what constituted the miniature painters' palette in the Timurid period.

The Devonian Hera metaturbidite-hosted polymetallic Au–Zn–Pb–Ag deposit of central NSW, Australia, contained a total undepleted resource of 3.6 Mt @ 3.3 g/t Au, 25 g/t Ag, 2.6% Pb and 3.8% Zn. The deposit comprises a number of distinctive lodes with each containing a distinctive ore and alteration/gangue mineralogy, though generally the sulfide ore comprises various mixtures of sphalerite, galena, chalcopyrite, pyrrhotite and relatively common visible gold–electrum. The North Pod and Far West lodes are distinctly Sb rich and contain a more diverse ore mineralogy with arsenopyrite, native silver, native antimony, gudmundite, tetrahedrite-(Fe), argentotetrahedrite-(Fe), acanthite, dyscrasite, nisbite and breithauptite. From analysis of 52,760 assays from across the deposit it was found that there was a very poor correlation between gold and each of Fe, Zn, S, Pb, Cu, As and Ag, whereas Ag correlated reasonably well with both Pb and Zn. Results from EPMA shows that gold varies widely in composition from host-rock associated gold (96 wt.% Au) through more intermediate compositions (88–73 wt.% Au) to electrum (46–27 wt.% Au), commonly associated with Sb-phases and containing significant Sb within the gold itself (1.05–2.58 wt.% Sb). From the Far West lense, aurostibite occurs as distinctive rims around gold. Although aurostibite associated with gold contains no silver, the gold itself contains constant moderate amounts (10.87–12.27 wt.% Ag). We suggest that the aurostibite and other Sb phases formed from a late-stage Sb-rich hydrothermal during low-temperature retrograde skarn alteration. There is abundant evidence for both chemical and physical remobilisation at Hera and this remobilisation is largely responsible for the spectrum of gold compositions observed. The source for these fluids may be an underlying magmatic body, evidence for which occurs as granite pegmatite dykes in various locations throughout the deposit. Furthermore, gold with a moderate to high Sb content may be indicative of a low temperature of formation.

Sophisticated metrological systems were common in the European Bronze Age and mass-regulation has been argued for various classes of object, including gold artefacts. A recent study published in Antiquity used Cosine Quantogram Analysis to demonstrate mass-regulation in a small sample of gold objects from Britain, Ireland and France. Since then, substantial quantities of new data from British Bronze Age gold objects have been collated. Here, the author presents the results of Cosine Quantogram Analysis on nearly 1000 such objects—the largest sample analysed to date. The results demonstrate that, even though some regularities can be discerned, mass-regulation is no longer a tenable interpretation of gold objects from Bronze Age Britain.

Why has gold persisted as a significant reserve asset despite momentous changes in international monetary relations since the collapse of the classical gold standard? IPE theories have little to say about this question. Conventional accounts of international monetary relations depict a succession of discrete monetary regimes characterized by specific power structures or dominant ideas. To explain the continuous importance of gold, we draw on insights from social psychology and new materialist theories. We argue that international monetary relations should be understood as a complex assemblage of material artifacts, institutions, ideas, and practices. For much of its history, this assemblage revolved around the pivotal practice of referencing money to gold. The centrality of gold as experienced by policymakers had important effects. Using archival and other evidence, we document these effects from the 1944 Bretton Woods conference through the transition to floating exchange rates in the mid-1970s; most IPE scholars underestimate the role of gold during this period. Power relations and economic ideas were obviously important, but they contributed little to a fundamental development: the long process of reluctantly coming to terms with the limitations of specie-backed currency, and the progressive and still ongoing decentering of gold in international monetary relations.