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This paper reports novel data concerning the volcanic formation of thePiperno, a stone that has been used for a long time in the monumental architecture of Naples and the Campanian region (Southern Italy). A careful field survey of the outcrops or underground sites so far accessible allowed us to draw a lithostratigraphic reconstruction of the formation and enabled the recognition of the three main layers exploited in past centuries and which provided dimension stones for architectural and structural purposes. Petrophysical and mineralogical characterization also enabled us to discriminate the same layers previously identified. Different scoriae/matrix ratio, scoriae dimension and welding degree are the most peculiar features of these horizons. The combination of these three parameters, even though they did not affect the use ofPipernoas dimension stone, somehow determined its variable susceptibility to the weathering agents. However, a linear relationship between the exposure time and the decay of the stone itself, at a parity of weathering intensity, was not observed. This assumption was proved by verifying that the specific layers of the volcanic sequence controlled the weathering degree ofPipernofrom monuments disregarding their age of emplacement. [ABSTRACT FROM AUTHOR]

The results of the geological characterization of an old stone building in southern Italy, are presented here. The Mondragone marble is a slightly metamorphosed carbonate rock, which was widely employed as monumental stone in the 18th century Royal Palaces of Naples and Caserta. In this paper, for the first time, this rock has been investigated with a thorough laboratory testing program, aimed at defining its mineralogical, physical and mechanical parameters. The two most important varieties of Mondragone marble were separately tested: the yellow and grey marbles (hereafter, YM and GM, respectively). The results obtained from physical tests (open porosity, dry density, specific gravity, water absorption coefficients, ultrasonic velocity) did not show marked differences between the two materials; in contrast, the mechanical strength tests (uniaxial compressive strength, point load strength, flexural strength) showed better behaviour of YM than for GM. After a tentative comparison with other well known carbonate rocks from Italy, some considerations on the response of Mondragone marble to local weathering were conducted. In particular, the weathering typologies were related to the particular texture of the brecciated marble and the different strength resistances displayed by the various constituents of the rock. [ABSTRACT FROM AUTHOR]

The crystal structure, crystal chemistry, and low-temperature structural evolution of natural thomsonite from Terzigno, Somma-Vesuvius volcanic complex, Naples Province, Italy, have been investigated by means of in situ single-crystal X-ray diffraction, electron microprobe analysis in the wavelength dispersive mode, and Raman spectroscopy. Six structure refinements have been obtained at different temperatures: 295.5, 248.0, 198.0, 148.0, 98.0, and 296.0 K (after the low-T experiments). The reflection conditions and the structure refinements prove that the crystal of thomsonite here investigated is orthorhombic with a = 13.0809(3), b = 13.0597(3), c = 6.6051(1) Å, V = 1128.37(14) Åsup3;, and space group Pbmn, which differs from thomsonite from different localities reported in previous studies (with a ~ 13.1, b ~ 13.06, c ~ 13.2 Å, and space group Pncn). The refined bond distances suggest that the Si/Al-distribution in the tetrahedral framework is fully "disordered," giving rise to the halving of the c axis relative to that found in "ordered" thomsonites. The extra-framework population consists of: (1) one site about 50% occupied by Ca (labeled as "Ca"); (2) one site occupied by Na (~70%) and Ca (~30%) (labeled as "Na"); and (3) three water molecule sites ("W1," "W2," "W3"). The structure refinements allowed the location of all the proton sites, and the hydrogen-bonding scheme in the structure is provided. The low-temperature refinements show no significant change in the structure within the T-range investigated. The evolution of the unit-cell volume with T exhibits a continuous and linear trend, without any evident thermo-elastic anomaly, with thermal expansion coefficients αV = V-1·∂V/∂T= 20(2)·10-6 K-1 (between 98.0 and 295.5 K). A list with the principal Raman active modes is provided and a comparison with the vibrational modes previously found for "ordered" thomsonite is carried out. [ABSTRACT FROM AUTHOR]