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Platinum placer dposits of the Seinav-Galmoenan Ore Complex, Koryak Foldbelt, Far East Russia: Mineralogy and tectonic aspects of the origin
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
A.G. Mochalov, V.P. Zaitsev, A.N. Pertsev
The placer PGE minerals mainly occur as anhedral aggregates intergrown with chromespinel, olivine, pyroxene (diopside-hedenbergite), amphibole, and others. A total of 25 different minerals were identified, dominated by isoferroplatinum (Table 1). The economic potential of the placers is defined by the wt.% of PGM in each grain-size fraction, the density, and the content of the silicate and chromespinel inclusions (Table 2). Furthermore, total PGE concentrations in the placer sands were determined by neutron-activation analyses, and are illustrated in Table 3.
Lexicon of lithostratigraphic units for the Sudan
Published in J.R. Vail, Lexicon of Geological Terms for the Sudan, 2022
It comprises about 8 migrating and overlapping intrusive centres made up of about 23 recognizable phases, including that of Abu Siba to the north. They are dominantly alkali granites and microgranites, alkali syenites, quartz syenites, hedenbergite syenites, augite- and hornblendesyenites. Volcanic rocks are not preserved, but screens of basement gneiss have been caught up between the ring-dykes. The complex extends ESE over 13 km and is accompanied by radial and arcuate dykes.
Properties of the Elements and Inorganic Compounds
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Name Danburite Datolite Daubreelite Derbylite Diaspore Digenite Diopside Dioptase Dolomite Douglasite Dyscrasite Eddingtonite Eglestonite Emplectite Enargite Enstatite Epidote Epsomite Erythrite Eucairite Euclasite Eudialite Eulytite Euxenite Ferberite Fergussonite Fluorite Franklinite Gahnite Galaxite Galena Galenabismuthite Ganomalite Gaylussite Geikielite Gibbsite Glauberite Glauconite Glaucophane Gmelinite Goethite Greenockite Grossularite Gypsum Halite Hambergite Hanksite Harmotome Hausmannite Haüyne Hedenbergite Helvite Hematite Hemimorphite Herderite Hessite Heulandite Hornblende Huebnerite Humite Formula CaB2Si2O8 CaBSiO4(OH) Cr2FeS4 Fe6Ti6Sb2O23 AlO(OH) Cu1.79S CaMg(SiO3)2 CuSiO2(OH)2 CaMg(CO3)2 K2FeCl42H2O Ag3Sb BaAl2Si3O104H2O Hg4OCl2 CuBiS2 Cu3AsS4 MgSiO3 Ca2Al2FeOH(SiO4)3 MgSO47H2O (Co,Ni)3(AsO4)28H2O AgCuSe BeAlSiO4(OH) (Na,Ca,Ce)5(Fe,Mn)(Zr,Ti) (Si3O9)2(OH,Cl) Bi4(SiO4)3 (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6 FeWO4 (Y,Er,Ce,Fe)(Nb,Ta,Ti)O4 CaF2 ZnFe2O4 ZnAl2O4 MnAl2O4 PbS PbBi2S4 (Ca,Pb)10(OH,Cl)2(Si2O7)3 Na2Ca(CO3)25H2O MgTiO3 Al(OH)3 Na2Ca(SO4)2 (K,Na,Ca)1.6(Fe,Al,Mg)4.0Si7.3Al0.7O20 (OH)4 Na2Mg3Al2[Si8O22](OH)2 (Ca,Na2)[Al2Si4O12]6H2O FeO(OH) CdS Ca3Al2(SiO4)3 CaSO42H2O NaCl Be2(OH,F)BO3 Na22K(SO4)9(CO3)2Cl Ba[Al2Si6O16]6H2O Mn3O4 (Na,Ca)4-8Al6Si6O24(SO4,S)1-2 CaFe(SiO3)2 Mn4Be3Si3O12S Fe2O3 Zn4(OH)2Si2O7H2O CaBe(PO4)(Fe,OH) Ag2Te (Ca,Na2,K2)[Al2Si7O18]6H2O Ca2(Mg,Fe)4Al(Si7AlO22)(OH)2 MnWO4 Mg(OH,F)23Mg2SiO4 Crystal system rhombohedral monoclinic cubic rhombohedral orthorhombic cubic monoclinic rhombohedral rhombohedral orthorhombic rhombohedral rhombohedral cubic rhombohedral rhombohedral monoclinic monoclinic orthorhombic monoclinic orthorhombic monoclinic hexagonal cubic rhombohedral monoclinic tetragonal cubic cubic cubic cubic cubic rhombohedral hexagonal monoclinic hexagonal monoclinic monoclinic monoclinic monoclinic hexagonal orthorhombic hexagonal cubic monoclinic cubic rhombohedral hexagonal monoclinic tetragonal cubic monoclinic cubic hexagonal rhombohedral monoclinic orthorhombic monoclinic monoclinic monoclinic orthorhombic /g cm-3 3.0 2.98 3.81 4.53 3.4 5.55 3.30 3.5 2.86 2.16 9.74 2.8 8.4 6.38 4.5 3.19 3.44 1.67 3.06 7.7 3.1 3.0 6.6 5.5 7.51 5.7 3.18 5.21 4.62 4.04 7.60 7.04 5.6 1.99 3.85 2.42 2.80 2.7 3.19 2.10 4.3 4.8 3.59 2.32 2.17 2.36 2.56 2.44 4.84 2.47 3.53 3.32 5.25 3.45 2.98 8.4 2.2 3.24 7.2 3.3 Hardness n 7 1.63 5.3 1.624 5 6.8 2.8 6 5 3.5 3.8 2.5 2 3 5.5 6 2.3 2 2.5 7.5 5.5 4.5 6 4.3 6 4 6 7.8 7.8 2.5 3 3.5 2.8 5.5 3 2.8 2 6 4.5 5.3 3.3 6.8 2 2 7.5 3.3 4.5 5.5 5.8 6 6 6 5 5.3 2.5 3.8 5.5 4.3 6 2.45 1.694 1.680 1.65 1.500 1.488 1.541 2.49 n 1.63 1.652 2.45 1.715 1.687 1.70 1.679 1.500 1.553
Rocky relationships: the petroglyphs of the Murujuga (Burrup Peninsula and Dampier Archipelago) in Western Australia
Published in Australian Journal of Earth Sciences, 2019
E. R. Ramanaidou, L. C. Fonteneau
The elongated, prismatic and lamellar clinopyroxenes crystals (augite) belong to the diopside–hedenbergite series with an Mg/Fe ratio of 1.25 diagnostic of tholeiites. The observed lamellae along the cleavages are chloritic with rare actinolite. Quartz crystals (mean size 300 µm) crystallise between augite and labradorite (Figure 8). Hickman (2001) interprets the interstitial quartz as owing to inclusions of remelted granitoids at the base of the gabbroic unit. Sub-euhedral ilmenites (Table 2), replaced by sphene (Table 2) and rutile along fractures, are commonly associated with euhedral apatite (Table 2) disseminated in the rock. In summary, all minerals described here are igneous, or metasomatic equivalents, and were formed by fractional crystallisation from an enriched tholeiitic magma. This gabbro also suffered hydrothermal alteration, with some slight clastic deformation. Secondary minerals (Table 2) include dominant chlorite and amphibole and minor epidote, phengite, rutile and barite. Chlorite, as ripidolite, replaces augite and labradorite along the cleavages and around sphene (Figure 8).
Contemporaneously emplaced submarine volcaniclastic deposits and pillow lavas from multiple sources in the island arc Brook Street Terrane, Southland, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2020
Jasmine F. Mawson, James White, James Michael Palin
Major element geochemistry confirms the mineralogy identified in thin section (Table 1). Representative samples of the data used to construct the following figures are available in the supplemental material. The majority of clinopyroxenes are compositionally classified as augite or diopside, although one analysed is hedenbergite (Figure 5). Most feldspars are albite (Figure 6), suggesting metamorphic albitizaton of originally more anorthite-rich feldspars (Spandler et al. 2003). Less common K-feldspar is secondary and occurs as small crystals in the matrix of the clastic rocks. Pillow lavas lack K-feldspar, whereas in dikes both of the feldspars occur in phenocrysts zoned from plagioclase to K-feldspar (probably secondary).
Petrogenetic links between the Dunedin Volcano and peripheral volcanics of the Karitane Suite
Published in New Zealand Journal of Geology and Geophysics, 2018
Oliver E. McLeod, James D. L. White
Clinopyroxene compositions span from diopside to hedenbergite and augite on the En–Wo–Fs ternary diagram (Figure 8A). Basanite and trachyandesite form two distinct groups within the diopside field and at the diopside–hedenbergite boundary respectively. In phonolite, the clinopyroxenes are compositionally diverse and span all three fields with some crystals of similar composition to those in basanite and trachyandesite. The variation plots for clinopyroxene in Figure 9A–D shows that basanite forms discrete compositional groups defined by high-MgO and TiO2 (A), small variation for FeO (6–12 wt%; B), low-Na2O–MnO trend (C) and very narrow CaO content with large variations in Cr content. In trachyandesite, by contrast, the clinopyroxenes have low TiO2 (A) and FeO (B) contents, form a high MnO trend with phonolite (C) and are Cr poor relative to basanite. The clinopyroxenes within phonolite are divided into two compositional groups; (1) low-TiO2, high-FeO, high-Na2O–MnO and relatively high clustered CaO (21–22 wt%) and Cr contents (0.04–0.1 wt%); and (2) high-MgO–TiO2, relatively low FeO (7–11 wt%) , low Na2O–MnO and low-Cr (near 0 wt%). The first group shows some affinity with the clinopyroxenes in trachyandesite, namely the continuous trends in MgO–TiO2 and Na2O–MnO in plots A and C. However, the clinopyroxenes in phonolite are significantly more iron-rich, as observed in the classification diagram (Figure 8A). The second clinopyroxene group in phonolite (dotted lines in plots A–C, Figure 9) is strongly correlated with the basanite group (high MgO–TiO2, moderate FeO 8–12 wt%, low Na2O–MnO) and these crystals evidently represent the diopsidic clinopyroxenes identified in Figure 8A.