Slaking characteristics of pyrite-bearing mudstone based on mineral compositions

The X-ray diffraction analysis (XRD) and wet-dry slaking test were examined to clarify mudstone weathering and slaking characteristics using drilling cores of the Lower Cretaceous Fujikawa Formation distributed in the Katsuura-gawa area, Tokushima, Japan. The drilling cores of the Fijikawa Mudstone were subdivided into three weathering grades as in the Fresh-zone, Slightly- and Strongly-weathered zones by naked-eye observations. The peaks of quartz, feldspar, calcite, illite and chlorite were detected by XRD analysis of the mudstone. The amount of calcite decreased in relation with the progressing of weathering grade, whereas the amounts of other minerals are constant during the weathering. Pyrite micrograins were extracted by the chemichal-etching process of mudstones. * The laboratory experiments and field observations revealed that the wet-dry slaking occurs in the Fujikawa Mudstone without swelling-clay minerals such as smectite. These characteristics of slaking originate from the changes of rock texture and physical properties of the mudstone with the oxidation of pyrite micrograins and dissolution of calcite under the oxidizing condition

Extracting-method of pyrite micrograins as an indicator for mudstone weathering

Applying to the indicator of mudstone weathering, an extracting method of pyrite micrograins and the secondary materials formed by oxidation and hydroxidation was examined using water diluted HF (3%). Based on the condition of extracted materials, the weathering grade of the drilling-cores of the Lower Cretaceous Fujikawa Shale Formation was subdivided into Oxidized- (weathered), Fresh-Oxidized Coexistence-, and Fresh- (non-weathered) zones in the order from the ground surface. The Fresh Zone is identified by only occurrence of non-altered primary pyrite micrograins that originate a bio-chemical process in sedimentary stage, and are characterized by aggregation of framboidal (raspberry-like), tubal (pellet-like), cubic and dodecahedral shapes. In the Fresh-Oxidized Coexistence Zone, pyrite micrograins and the secondary materials (hematite, goethite and limonitic hydrous ferric oxides) formed by oxidation and hydroxidation of pyrite co-exist, whereas the Oxidized Zone is characterized by the occurrence of ferric secondary materials without primary pyrites. A pyrite-alternation model was proposed in relation with the progressing of slaking. The Extracting-method of pyrite micrograins is useful even the case that the pyrite peak is not detected by X-ray analysis because of lower containing percentage

Mannose-specific lectin from the mushroom Hygrophorus russula

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