Ricerc@Sapienza

Fibrous erionite is a naturally occurring zeolite considered to be highly carcinogenic upon inhalation, even more than crocidolite. Since no iron is typically present in erionite, its toxicity has been attributed to ion-exchanged Fe participating in Fenton chemistry. Recently, a study aimed at investigating possible fiber inactivation routes surprisingly showed that, despite having completely occluded all available pores with K ions, the erionite-Na sample preserved the property to upload Fe (II) within the structure.

The thermal behaviour of sacrofanite, the ABCABACACABACBACBACABABACABC 28-layer member of the cancrinite sodalite supergroup has been investigated in situ using laboratory focussing-beam X-ray powder diffraction data. Thermal expansion has been analysed from 303 to 873 K. A moderate anisotropy has been observed at T > 473 K, the c-parameter being softer than the a-parameter. At ca. 800 K the unit cell starts to compress owing to (partial) dehydration.

The thermal behavior of a woolly erionite-K sample (Lander County, NV, USA), chemical formula (Ca2.03 Na0.73 K2.52 Mg0.26)[Al8.22 Si27.78 O71.80 ]·35.94H2 O, was investigated in the 303–1173 K thermal range by in situ X-ray powder diffraction. Present data suggest a general thermally-induced volume contraction whose magnitude increases as(formula presented) ratio becomes smaller. An inverse correlation between(formula presented) ratio and Tdehydr is observed because higher(formula presented) ratio values are associated to lower dehydration temperatures.

In the present work we report the full structural and spectroscopic characterization of an UICC crocidolite standard sample, that is a fibrous riebeckite from Koegas Mine, Northern Cape (South Africa). The chemical composition was obtained by SEM-EDS and cation site partition was retrieved by complementing chemical, Mössbauer and X-ray powder diffraction data. Cell parameters, fractional coordinates, and site scattering for M(1), M(2), M(3), M(4) were refined using the Rietveld method.

This study is focused on the Red Slip Ware from the archaeological site of Sulky (Sardinia, Italy), dated back to the end of 9th to the early 8th centuries B.C. Optical Microscopy (OM), X-ray Powder Diffraction (XRPD) and Scanning Electron Microscopy coupled with an EDS system (SEM-EDS) were used to characterize both the body and the external Red Slip decoration.