Alteration clay mineral

Finally, some soils contain relatively high proportions of zeohtes ( 15%). These result again from arid or semiarid environments where evaporation produces a high concentration of sodium carbonate, which can alter clay minerals to produce zeolites. Examples of this are the heulandite found in the Harwell soil series in Southern England and the analcime in the San Joaquin Valley (California). 

Description soils with abundant iron oxides crystallized but primary minerals not completely altered. Clay minerals with 1 1 structure. 

The disadvantage of this procedure is that the minerals maybe physically or chemically altered during burning. Eor example, the refractive index of clay minerals is changed the color, birefringence, and pleochroism of micas is altered carbonates are destroyed and the iron sulfides are oxidized to iron oxides. 

Mixed layer clay mineral (sericite/smectite) is found in Kuroko ore bodies and altered dacitic rocks underlying the ore. This mineral is thought to have formed by the... 

Zeolite minerals (wairakite, laumontite etc.), mixed-layer clay minerals and sme-cite occur in the upper part of the propylitically altered rocks (e.g., Seigoshi, Fuke, Kushikino), but they are sometimes poor in amounts. Generally carbonates are more abundant in the mine area as in the Toyoha district. Temporal relationship between the formation of high temperature propylitic alteration minerals (epidote, actinolite, prehnite) and low temperature propylitic alteration minerals) (wairakite, laumontite, chlorite/smectite, smectite) in these areas (Seigoshi, Fuke, Kushikino) is uncertain. 

Izawa et al. (1990) recognized the following alteration zones from the vein towards margin of the Hishikari Au-Ag mine area, chlorite-sericite zone (zone IV), interstratified clay mineral zone (zone III), quartz-smectite zone (zone II) and cristobalite-smectite zone (zone I) and least altered zone (L.A. (least altered) zone) (Fig. 1.131). 

Shirozu, H. (1974) Clay minerals in altered wall rocks of the Kuroko-type deposits. In Ishihara, S. (ed.). Geology of Kuroko Deposits, Mining Geology Special Issue, 6, 303-310. 

Steiner, A. (1968) Clay minerals in hydrothermally altered rocks at Wairakei, New Zealand. Clays Clay Minerals., 16, 193-213. 

The dominant alteration minerals at the deeper part of the well include anhydrite, epidote, sericite, chlorite, calcite, dolomite, rhodochrosite, kutnahorite, zeolites (mordenite, clinoptilorite), chlorite and sericite/smectite interstratified clay mineral with subordinate amounts of kaolinite in the shallower part (Imai et al., 1996). 

Collins, Y.E. and Stotzky, G., Heavy metals alter the electrokinetic properties of bacteria, yeasts, and clay minerals, Appl Environ Microbiol, 58 (5), 1592-1600, 1992. 

Some of the clays that enter the ocean are transported by river input, but the vast majority of the riverine particles are too large to travel fer and, hence, settle to the seafloor close to their point of entry on the continental margins. The most abundant clay minerals are illite, kaolinite, montmorillonite, and chlorite. Their formation, geographic source distribution and fete in the oceans is the subject of Chapter 14. In general, these minerals tend to undergo little alteration until they are deeply buried in the sediments and subject to metagenesis. 

After delivery to the ocean, clay minerals react with seawater. The processes that alter the chemical composition of the terrigenous clay minerals during the first few months of exposure are termed halmyrolysis. These include (1) cation exchange, (2) fixation of ions into inaccessible sites, and (3) some isomorphic substitutions. Another important transfiarmation is flocculation of very small (colloidal-size) clay particles into larger ones. 

During this zone refining, the primary (igneous) rocks are transformed into secondary minerals. These include (1) clay minerals, such as phillipsite, chlorite, montmo-rillonite (smectite), saponite, celadonite, and zeolite (2) iron oxyhydroxides (3) pyrite (4) various carbonates and (5) quartz. These minerals form rapidly, within 0.015 and 0.12 million years after creation of the oceanic crust at the MOR. During these alteration... 

The palagonite is thermodynamically unstable and, hence, reacts with seawater to form various clay minerals, including smectites (montmorillonite, nontronite, and saponite), micas (celadonite), and zeolites (phillipsite). This chemical weathering involves uptake of Si, Al, Mg, Ca, Na, and K and the release of water, reversing to some extent, the elemental effect of palagonitization. These mineral alterations tend to proceed progressively from the outer margin of the pillow basalts to their interior. 

Halmyrolysis The processes that alter the chemical composition of terrestrial clay minerals during their first few months of exposure to seawater. 

A heterogeneous natural system such as the subsurface contains a variety of solid surfaces and dissolved constituents that can catalyze transformation reactions of contaminants. In addition to catalytically induced oxidation of synthetic organic pollutants, which are enhanced mainly by the presence of clay minerals, transformation of metals and metalloids occurs with the presence of catalysts such as Mn-oxides and Fe-containing minerals. These species can alter transformation pathways and rates through phase partitioning and acid-base and metal catalysis. 

Clay minerals are ubiquitous up to hundreds of metres from hydrothermal U mineralization, and often there is zoning in the type of alteration minerals (Hoeve Quirt 1984). These can be mapped with remote sensing that can detect in the visible and the middle-infrared sections of the electromagnetic spectrum (Earle et al. 1999). The two oxidation states of U and Fe have been proposed to map bleached... 

FIoeve, J. Quirt, D.FI. 1984. Mineralization and Flost Rock Alteration in Relation to Clay Mineral Diagenesis and Evolution of the Middle- Proterozoic, Athabasca Basin, northern Saskatchewan, Canada. Saskatchewan Research Council, SRC Technical Report 187, 187 p. 

For oxygen this means a decrease in from an initial 5-valne very near 0%c (ocean water) to abont -2%o at depths aronnd 200 m (Perry et al. 1976 Lawrence and Gieskes 1981 Brnmsack et al. 1992). Even lower 5 0-values of about -4%c at depths of around 400 m have been observed by Matsumoto (1992). This decrease in 0 is mainly dne to the formation of anthigenic 0-enriched clay minerals such as smectite from alteration of basaltic material and volcanic ash. Other diagenetic reactions inclnde recrystallization of biogenic carbonates, precipitation of... 

Abdelouas, A., Crovisier, J. L., Lutze, W., Fritz, B., Mosser, A. Muller R. 1994. Formation of hydrotalcite-like compounds during R7T7 nuclear waste glass and basaltic glass alteration. Clays and Clay Minerals, 42, 526-533. 

---