“Mohsite” of Colomba: Identification as Dessauite-(Y)

[摘要] During a reorganization of the mineralogical collection of Turin University, old samples of the so-calledmohsiteof Colomba were found. “Mohsite” was discredited in 1979 by Kelly et al., as a result of some analyses performed on the equivalent material coming from the French region of Hautes-Alpes, but the original samples found in similar geological setting in Italy were lost and never analysed with modern equipment. After more than a century, the rediscovered samples of Professor Colomba were analysed by means of SEM-EDS analysis, microRaman spectroscopy, and X-ray diffraction. The results have demonstrated that the historical samples studied by Colomba are Pb-free dessauite-(Y), and pointed to an idealized crystal chemical formula (Sr0.70Na0.25Ca0.09)Σ=1.04(Y0.62U0.18Yb0.09Sc0.08)Σ=0.97  Fe22+(Ti12.66Fe4.783+V0.263+)Σ=17.70O38and unit-cell parametersa= 10.376(3) Å,c= 20.903(6) Å, andV= 1949(1) Å3.

[学科分类] 地质学