The modes of occurrence of six rare-earth elements (La, Ce, Sm, Eu, Yb, and Lu) in low-rank coals (lignites and sub-bituminous coals; also referred to as brown coals) from different deposits...

We have first determined the contents of rare-earth elements and yttrium (REY) in four major mineral fractions of hydrothermal sedimentary ferromanganese crusts of the Sea of Japan. It is shown that REY are sorbed mostly by Fe oxyhydroxides (FeOOH). The REY content in the residual aluminosilicate fraction is the second most important factor determining the crust composition. The manganese fractions, composing more than 80 vol.% of the crusts, plays a subordinate role in REY accumulation. The REY pattern of hydrothermal sedimentary crusts in back-arc basins depicts the sum of the REY contents of the FeOOH fraction (hydrogenous) and residual fractions containing the total REY of the products of bedrock disintegration and endogenous (pyroclastic material) and exogenous (desert dust) components.

17 samples, including 16 coal-seam samples and one parting, were collected from 4 mines in Ningdong Coalfield, west Ordos Basin, China. Maceral, mineralogy and geochemistry of them were studied by using of optical microscope, LTA-XRD (low temperature ashing-X-ray diffraction), XRF (X-ray fluorescence), and ICP-MS (Inductively coupled plasma mass spectrometry). The results indicate that Ningdong Jurassic coal is a medium volatile bituminous coal, with medium-ash, medium-sulfur and low-medium-calorific. The vitrinite of them is much higher, while the inertinite and liptinite are less, than that of other Early-Middle Jurassic in Ordos Basin. The minerals consist of abundant of quartz, kaolinite, illite, albite, and trace of chamosite, calcite, pyrite. Kaolinite, illite, chamosite, quartz, and albite are origin from weathering productions of gneiss, granulite and granite in Helan Moutain. The coals are enriched by Na₂O, MgO, K₂O, MnO, Ga, Cr, Rb, Sr, Cd, and Ba in comparison with Chinese average abundances of elements in coals. The major carriers Na₂O, MgO, K₂O are clay minerals and albite. The hazardous trace elements, Cd and Cr occur in organic matter and clay mineral, respectively. The rare metals, Ga and Rb are associated with clay mineral. The medium REY are enriched in the coal.

This paper presents the first results of petrochemical and geochemical studies (by the ICP-MS technique) of adakites comprising a small extrusive body in the Ilistaya River basin (West Primor’e)....