Poorly-crystalline minerals and complex mineral assemblages

摘要: Minerals formed in the weathering environment are often characterized by effects of crystalline imperfection: superparamagnetism, foreign element substitution, and close intergrowths different mineral species frequently complicate their identification Mossbauer spectroscopy. Because these effects, spectra taken at 77 K may not be sufficient to distinguish between iron oxides silicates, have 4.2 or even lower temperatures order fulfill this purpose. Chemical extraction procedures help separate constituents mineralogically complex samples, but some can reduce structural iron(III) clay minerals iron(II), thus creating artefacts.