Naslov
Heating products of glauconitic materials

Autori
Slovenec, Dragutin ; Popović, Stanko ; Tadej, Neven

Izvornik
Neues Jahrbuch für Mineralogie : Abhandlungen (0077-7757) 171 (1997), 3; 323-339

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
glauconite; glauconitic materials; glauconites-smectites; heating products of glauconitic materials; magnesioferrite; hematite; enstatite; lower miocene sandstones from Hrvatsko Zagorje

Sažetak
Four practically pure, mutually chemically different, glauconitic materials, as mixtures of glauconite and interstratified glauconites-smectites (having relatively small expandibility) were isolated from the Lower Miocene sandstones at several localities in Croatia. Glauconitic materials were successively heated for 3 horus at 980, 1080, 1180, and 1300^oC. The heat-traeted samples were analysed by means of X-ray powder diffraction (identification, determination of the unit-cell parameter a of magnesioferrite and semiquantitative phase analysis). The amounts of FeO in samples were also determined. On the basis of the data obtained for the heat-treated samples and the data on the starting glauconitic materials (using the “wet” chemical analysis, infrared spectroscopy, differential thermal analysis and thermogravimetry, beside X-ray diffraction), the following conclusion was drawn: (1) after the destruction of the crystal structure of glauconite, the heating products at 980^oC were an amorphous fraction (glass) and magnesioferrite ; (2) in the materials for which the content of Fe^3+ was much bigger than that of AlˆVI, magnesioferrites were formed which were solid solutions of MgFe_2O_4, gama-Fe_2O_3 and Fe_3O_4 ; otherwise, in the material with a high amount of AlˆVI a magnesioferrite was formed which also contained Al ; (3) the fraction of magnesioferrite gradually decreased as the temperature of heating increased to 1080 and 1180^oC, while hematite and enstatite were formed ; (4) after heating at 1300^oC magnesioferrite was again the single crystalline phase, but containing a bigger amount of divalent iron and having a bigger unit-cell parameter a than magnesioferrite formed at 980^oC.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Kemija

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