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The article highlights the Albert Chapman Mineral Collection displayed at the Australian Museum in Sydney, New South Wales. The Albert Chapman mineral collection was regarded as one of the top ten private mineral collections in the world when most of it was purchased from him by the New South Wales Government in 1988. Many of the Broken Hill specimens, such as rhodonite, cerussite, smithsonite, pyromorphite, azurite, anglesite, and spessartine, are among the best ever found from this famous mining region.

This paper reports the mineralogy and geochemistry of the Late Permian C1 Coal from Bole and Laibin mines in eastern Yunnan, Southwestern China (C1 Coal in Laibin mine is composed of three layers termed B1, B2, and B3). The coals are characterized by medium-high ash yields and very low sulfur contents. Compared with average values of trace element concentrations in hard coals worldwide, the Bole and Laibin coals are enriched in V, Co, Cu, Zn, and Se, which were mainly derived from the sediment-source region of the Kangdian Upland. Major minerals in the coal samples and roof and floor strata include quartz, interstratified berthierine/chamosite (B/C), as well as kaolinite, mixed layer illite/smectite, calcite, pyrite, and anatase. Unlike a pure chamosite, the 7 Å peak of interstratified B/C is sharp and narrow, while the 14 Å peak is broad and weak, or absent in some coal samples. Interstratified B/C was largely precipitated from low-temperature Fe-rich and Mg-rich hydrothermal fluids or, in some cases, is an alteration product of kaolinite. Secondary phases of quartz, calcite, pyrite, kaolinite, chalcopyrite, gypsum, and REE-phosphates in the coal samples are the dominant authigenic minerals formed at syngenetic and early diagenetic stages. Four intra-seam partings in C1 Coal, B1, and B3 layers are identified as tonsteins derived from felsic volcanic ashes. These tonsteins consist mainly of cryptocrystalline kaolinite with graupen and vermicular textures, and minor amounts of high-temperature quartz, zircon, apatite, monazite, and anatase. The floor of the C1 Coal in the Bole mine is a tuffaceous claystone and consists of altered high-Ti basalt volcaniclastics, characterized by high concentrations of Zr, Nb, V, Co, Cu, and Zn, low Al2O3/TiO2 ratio (~4.62), high Ti/Y ratio (~900), enrichment of middle rare earth elements, and positive Eu anomalies. [ABSTRACT FROM AUTHOR]

Volcanic ashes in coal and coal-bearing sequences typically occur as persistent bands within coal seams (generally as tonsteins, but in a few cases as bentonites, K-bentonites, or as clay-free partings), as an intimate mixture with organic matter, as host rocks (such as roof and floor strata), or as thick layers in coal-bearing strata that are stratigraphically separated from coal seams, including those of thick, laterally persistent tuffs, and in the broader sense fragmental clay rocks and flint clays. Altered volcanic ashes have been found in numerous coals with rank ranging from lignite through various bituminous coals to anthracite, as well as in all the continents where coal beds are present. The main primary minerals in volcanic ash that survive post-depositional alteration include high-temperature quartz, plagioclase, sanidine, zircon, apatite, monazite, micas, rutile, and anatase. Alteration of volcanic glass and less stable primary minerals may result in the formation of kaolinite, smectite, illite, mixed-layer I/S and, in some cases, chlorite and zeolites. In addition to mineralogical and petrographic characteristics, identification of the parent magma type is commonly based on relatively immobile elements rather than the total alkali-silica contents, which are often affected by post-depositional alteration. Four types of volcanic ashes have been identified in coal and coal-bearing sequences, namely felsic, mafic, intermediate, and alkali. Altered mafic volcanic ashes are characteristically enriched in Sc, V, Cr, Co, and Ni; have positive Eu anomalies; and are of a medium-REE enrichment type. Altered alkali volcanic ashes are unique in their significant high concentrations of rare metals such as Nb, Ta, Zr, Hf, REE, and Ga, and are characterized by distinct negative Eu anomalies. Compared with altered alkali volcanic ashes, felsic tonsteins have relatively lower REE concentrations and less pronounced negative Eu anomalies, but a greater fractionation between light and heavy REEs. The compositional variation of different types of altered volcanic ashes is attributed to the tectonic framework and geodynamic controls. Volcanic ashes in coal may serve as chronostratigraphic markers to identify and correlate coal seams, and can also be used for radiometric age determination. The ashes may have provided terrigenous materials that served as substrates for peat development; and may have terminated peat accumulation if volcanic ash in large quantities fell into the peat swamp; they can also be used to indicate the geodynamic processes of coal formation; and perhaps explain mass extinction events. Admixed volcanic ash may lower the quality of the coal if not removed in the preparation plant. From a practical viewpoint, alkali volcanic ashes may be significantly enriched in rare earth elements, Y, Nb, Ta, Zr, Hf, and Ga, which have potential economic significance. This paper reviews the distribution, geochemical and mineralogical compositions, and the significance and applications of volcanic ashes in coal and coal-bearing sequences. [ABSTRACT FROM AUTHOR]

Volcaniclastic horizons near the Guadalupian-Lopingian Boundary (G-LB) from southwest China have attracted much attention, not only due to the End-Guadalupian mass extinction near the boundary, but also to the unique and regionally extensive Nb-Zr-REY-Ga mineralization with potential economic significance (REY = rare earth elements and Y). Previous studies have suggested that these horizons were derived from volcanism associated with the terminal phases of the Emeishan mantle plume, which however was not the only contemporaneous volcanic activity in southeast Asia at this time (~260 Ma). Here we present a systematic analysis focusing on the petrological, mineralogical, and geochemical features of the volcaniclastics from the Yiliang and Weixin boreholes from the lowest strata of the Late Permian Xuanwei and Longtan formations, respectively, eastern Yunnan, SW China. In addition, previous geochemical data obtained for the correlative layers near the investigated boreholes were used for reference. The mineralogy of the volcaniclastics is dominated by mixed-layer illite/smectite, illite, berthierine, kaolinite, and quartz, and to a lesser extent, albite, calcite, siderite, anatase, and hematite, along with traces of chamosite, rutile, and florencite. Additionally, zircon, pyrite, chalcopyrite, sphalerite, galena, rhabdophane, parisite, goyazite, and barite were identified under SEM-EDS. The values of Al 2 O 3 /TiO 2 in the volcaniclastic samples are mostly greater than eight, consistent with the characteristics of intermediate-felsic rocks. The Nb/Yb and Zr/TiO 2 vs. Al 2 O 3 /TiO 2 diagrams, and the chondrite-normalized REY distribution patterns of the samples collectively indicate that the Nb-Zr-REY-Ga mineralization was not only derived from the ELIP alkaline rocks, but also from the arc-related intermediate-felsic magmatic rocks from the Paleo-Tethys. However, the latter source for Nb-Zr-REY-Ga mineralization in SW China has not been previously reported. The two sources of clastic materials, i.e., from both within-plate/anorogenic magmatism and arc-related/orogenic magmatism, agree with previously-reported discrimination diagrams of ε Hf (t) vs. age and Hf/Th vs. Th/Nb in the zircon grains from the correlative claystones. In addition, the modes of occurrence of critical metals (Nb, Zr, REY, Ga) are identified in detail in this study. The results show that most of the HREE and almost all the Zr and Hf are in zircon; the LREE are dominantly in REE-bearing carbonates and phosphates; the Nb is largely in former Fe Ti oxide phases; and the Ga is predominantly in the clays. • Volcaniclastic horizons near G-LB are an extensive Nb-Zr-REY-Ga ore deposit. • The horizons originated from within-plate and arc-related magmatism. • The minerals in the horizons were dominantly altered from volcanic ashes. • The modes of occurrence of critical metals (Nb, Zr, REY, Ga) are revealed. [ABSTRACT FROM AUTHOR]

Peat depositional environments, the sites where and conditions under which peat accumulates, significantly influence a resultant coal's physical properties, chemical composition, and coal utilization behavior. Recognition of peat depositional environments for coal is a challenging endeavor because coal's observed compositional properties not only result from a variety of geological processes operating during peat accumulation, but also reflect the influence of adjoining or external depositional sedimentary environments and alteration during later diagenesis and/or epigenesis. The maceral or microlithotype composition of any one layer of peat can be the product of years or decades of plant growth, death, decay, and post-burial infiltration by roots in addition to the symbiotic, mutualistic, parasitic, and saprophytic relationships with non-plant biota, such as arthropods, fungi, and bacteria. The overprint of increasing thermal maturation and fluid migration through time on the resulting coal can make these relationships difficult to recognize. Therefore, published models based on maceral composition alone must be used with great caution. Lipid compositions, even from lipid-poor low-rank coals, can provide important information about depositional environments and paleoclimate, especially if combined with the results of organic petrography and paleontological studies. Just as sulfur derived from seawater provides environmental clues, the ratios of two particularly relevant trace elements rather than a single trace element can be used to interpret peat depositional environments. Epigenetic minerals, as well as their corresponding chemical compositions should not be used for such a purpose; similarly, resistant terrigenous minerals deposited during peat accumulation in many cases should be used with considerable caution. The interactions of the biota present in the peat-forming ecosystem, often determined using palynological and geochemical proxies, and their interpretation in the context of geography and paleoclimate are important means for deciphering peat depositional environments. Overall, a combination of evidence from geochemistry, mineralogy, palynology, and petrology of coal and from stratigraphy, sedimentology, and sedimentary facies of related rocks is necessary for accurate and comprehensive determination of depositional environments. The need for interdisciplinary studies is underscored by peat compositional properties, which have been greatly affected by various processes during the syngenetic, diagenetic or epigenetic stages of coal formation. [ABSTRACT FROM AUTHOR]

Coal, one of the most complex geological materials, consists of organic and mineral matter, the latter including crystalline minerals, non-crystalline mineraloids, and elements with non-mineral associations. Overall, the modes of occurrence of elements in coal are classified into organic, mineral, and intimate organic associations, the latter including those adsorbed on to the surface of organics, dissolved in pore waters, and hosted in very fine-grained minerals (sub-micro- or nano-minerals) encased in or shielded by the organic matter of coal. Mineral associations, defined as elements associated with minerals are straightforward; however, confusion about organic and intimate organic associations of elements usually arise in the literature. Understanding organic, mineral, and intimate organic associations of elements is important not only because non-mineral elements and, to a lesser extent, elements associated with fine-grained minerals, play a significant role in affecting the utilization of coal, but also such modes of occurrence of elements provide useful geochemical information on coal formation and coal-bearing basin evolution. With a few exceptions (such as Cd, Nb, Ta, Zr, and Hf), most elements determined in coal, particularly in low-rank coal, have varying-degrees of organic association. In this paper, we review the definition of associations of non-mineral elements in coal, as well as their methods of determination, and then review the associations of selected elements including environmentally-sensitive (e.g., S, As, U, and Hg) and critical elements, the latter of which drive some of the significant advancements in technology and energy efficiency in the world today (e.g., rare earth elements and Y, Ge, and U), and some major elements (e.g., Ca, Mg, Fe, Al, and Ti) that largely occur in non-mineral forms in low-rank coals. • The modes of occurrence of elements in coal are classified into organic, mineral, and intimate organic associations • The intimate organic associations include those adsorbed on to the surface of organics, dissolved in pore waters, and hosted in very fine-grained minerals. • Most elements determined in coal have varying-degrees of organic association. [ABSTRACT FROM AUTHOR]