First evidence of wulfenite in Calabria Region (Southern Italy)

This data article contains mineralogical and chemical data of the wulfenite (PbMoO4) sampled from mine of Fiumarella in Calabria region (Southern Italy). Wulfenite is a rare mineral belonging to the class of minerals called molybdates and if found in large amounts it can be used for the extraction of molybdenum. In the mine of Fiumarella, in addition to primary minerals such as barite, galena, cerussite, anglesite, fluorite and chalcopyrite, wulfenite was also detected. Wulfenite crystals are bipyramidal, few microns in size and grow as single crystals that can reach 1 mm. Methods for obtaining the data sets include optical microscopy, micro X-Ray Fluorescence and micro-Raman spectroscopy.


a b s t r a c t
This data article contains mineralogical and chemical data of the wulfenite (PbMoO 4 ) sampled from mine of Fiumarella in Calabria region (Southern Italy). Wulfenite is a rare mineral belonging to the class of minerals called molybdates and if found in large amounts it can be used for the extraction of molybdenum. In the mine of Fiumarella, in addition to primary minerals such as barite, galena, cerussite, anglesite, fluorite and chalcopyrite, wulfenite was also detected. Wulfenite crystals are bipyramidal, few microns in size and grow as single crystals that can reach 1 mm. Methods for obtaining the data sets include optical microscopy, micro X-Ray Fluorescence and micro-Raman spectroscopy.
& The data presented will allow to enrich the scientific knowledge of the wulfenite of Fiumarella mine (Catanzaro -Italy) for a possible extraction of molybdenum.
The data set can be used to valorize the location of Fiumarella, according to the Convention on the Protection of World, Cultural and Natural Heritage, adopted by UNESCO in 1972.
The data presented here may be used by other authors to compare composition, morphological features and Micro-Raman bands of other wulfenite crystals discovered in other parts of the world.
The data can be compared with those obtained from similar geologic environments and motivate studies on rare oxide minerals in the future.

Data
This data article contains mineralogical and chemical data of wulfenite (PbMoO 4 ) sampled from the barite mine of Fiumarella in Calabria Region (Southern Italy) (Fig. 1). The crystals of wulfenite were identified and characterized by optical microscopy, micro-Raman spectroscopy and micro X-Ray Fluorescence. Wulfenite occurs as a secondary mineral in the oxidation zones of hydrothermal lead deposits [1][2][3]. Wulfenite colour and morphology are shown in Fig. 2. A representative chemical analysis of wulfenite crystals is given in Fig. 3. The chemical composition of wulfenite as for the major constituents and some impurity elements is shown in Table 1. The characteristic Raman spectrum of the wulfenite and the its typical bands are shown respectively in Fig. 4 and Table 2.

Study area description
The Fiumarella mine (38°55'19.19" N, 16°34'25.71" E) is located in the western part of Catanzaro town, along Fiumarella Creek, in location Molino Mastricarro (Fig. 1). The area has been intensively exploited till the end of the eighties and about 5000 m of galleries have been excavated mainly to extract barite, fluorite, galena and chalcopyrite [1-3].

Optical microscopy
Specimens were investigated using a stereo binocular (Askania, GSZ 2 T, Germany) and images of the wulfenite crystals were acquired using a digital camera (Fuji X-E2, Japan). All the wulfenite crystals are yellow-honey in color with a greasy to resinous luster (Fig. 2) and appear to be idiomorphic forming bipyramidal tetragonal crystals. This morphology, similar to that found in the Austrian Bleiberg deposit [4], has been rarely detected worldwide. Based on the observation of several crystals, the bipyramid has a length to width ratio of about 3.5 to 1.5. Wulfenite crystals occur as overgrowth on a matrix containing white-grey, granular massive cerussite.

Micro X-Ray fluorescence (mXRF) data
Elemental semiquantitative analysis of the mineral were done using an M4 Tornado (Bruker Nano GmbH, Berlin, Germany). As regards chemical composition, the major elements include Pb and Mo (most intense peaks in the mXRF spectrum), chemically consistent with wulfenite composition (Fig. 3). In this regard, it is worth remembering that wulfenite is a mineral of broad economic importance due to its rarity and the extraction of molybdenum [5]. The semi-quantitative chemical composition of ten crystals as determined by mXRF are reported in Table 1. Note that the determined chemical composition deviates only slightly from the ideal formula PbMoO 4 . Specifically, the PbO 2 /MoO 3 ratio corresponds to 1.62, indicating a lower value than the theoretical value of 1.66 probably for the following reasons: i) mXRF chemical data are acknowledged to be semi-quantitative; ii) low amounts of Fe and As present as impurities deriving from the matrix are also detected (Table 1).

Micro-Raman spectroscopy data
Micro-Raman analyses were performed using a Thermo Fisher DXR Raman microscope (Waltham, MA, USA). Fig. 4 shows the Raman spectrum of the wulfenite crystals with typical bands at 172, 193, 319, 351, 745, 768 and 871 cm À 1 [6][7][8]; these data ( Table 2) are in agreement with the spectrum present in the RRUFF database named "R050024". The bands at 62, 72 and 102 cm À 1 (Fig. 4 and Table 2) also belong to wulfenite and they have been detected for the first time in this study.

Acknowledgments
The work has received financial support from the FFABR fund (by the Italian MIUR). mXRF analyses were performed at the "Micro Xray Lab" of the University of Bari (Italy), supported by Regione Puglia (Programma Operativo Regione Puglia -FERS 2000-2006 -Risorse Liberate -Obiettivo Convergenza).