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La possibilità che il sale avesse avuto un ruolo importante nelle dinamiche insediative del Carso e dell’Istria (Adriatico nord-orientale) fin dalla tarda preistoria è stata ipotizzata principalmente in base a indicatori indiretti, e non è stata validata finora da interventi di campo mirati. Indicatori indiretti quali l’accertato uso pastorale di parecchie grotte carsiche (pastorizia e sale sono legati dalla necessità di integrare l’alimentazione delle greggi di caprovini); la presenza di un numero alto di oggetti “esotici” in molti siti (oggetti dati / ricevuti in cambio di bestiame e sale?); dati etno-storici: presenza di impianti produttivi / saline sicuramente da epoca romana fino al secolo scorso lungo tutto il litorale (in Istria una salina è tuttora attiva). In età protostorica, alcuni materiali ceramici rinvenuti nel sito lungo costa di Stramare di Muggia e nel castelliere di Elleri sarebbero interpretabili come briquetage, e dunque costituirebbero prove dirette della produzione di sale. Nella letteratura specialistica sul sale sono considerati validi sia gli indicatori diretti sia quelli indiretti: nondimeno, la loro tipologia e l’uso esclusivo piuttosto che integrato degli stessi potrebbero costituire tema di discussione teorico-metodologica. L’individuazione di analisi archeometriche (lato sensu) tali da confermare la presenza / produzione di sale in ambienti idonei anche dal punto di vista geo-ambientale è un altro tema di possibile approfondimento, così come quello della dimensione diacronica del fenomeno sale, evidente dall’importanza che hanno in moltissimi casi i dati etno-storici.

Nineteen chromite crystals from the A, B, E, G, H, J and K chromitite layers of the Peridotite Zone of the Stillwater Complex (Montana, USA) have been studied by means of X-ray single crystal diffraction and microprobe analyses. The results show that samples from the basal A layer are quite different from the others showing very high oxygen positional parameter u (0.2633-0.2635) and Ti- contents (0.059-0.067 apfu). Mg# [(Mg/(Mg+Fe2+)]values are within the range 0.21-0.23 while for the other chromites it is in the range 0.45-0.57. Moreover, according to their structural parameters, samples from the other layers have been distinguished into two groups comprising, respectively, those from B, E, G, and those from H, J, K. It is supposed that high Fe2+ and Ti contents of A layer samples are due to the post-crystallization reaction with interstitial liquid. This fact allowed a very slow cooling rate as evidenced by the high u values. The fractionation of evolved magma from within the intrusion and pulse of a new magma bringing more chromium into the chamber lead to Cr- and Fe3+ -rich compositions and consequently to the increase of the cell edges. The decrease of u values seems to be related to the Cr+Fe3+ and/or Al contents.

Quite rare pottery shards showing a paste rich in black sand particles, possibly igneous minerals, have been discovered in late Republican Roman sites of Trieste area (NE Italy) and SW Slovenia in the Caput Adriae. Most of them belong to late Greco-Italic and Dressel 1 amphora types, in use from the end of the 3rd and the beginning of 1st centuries BC. Following a methodological procedure based on the analysis of igneous temper, proved to be particularly effective by several scholars, numerous minerals have been extracted from the surface of 16 pottery shards, without causing any visible damage to them. Microprobe analysis has allowed the identification of igneous minerals (olivine, clinopyroxene, feldspar and garnet), most likely originating from the Roman or Campanian magmatic provinces. The chemistry of garnets, indicated in the past as a possible tracer of ancient commerce but no longer used in the last decades to study Italian late Republican pottery, has proved to be a promising tool to distinguish among the two magmatic provinces. According to our study, most of the investigated garnets-bearing samples would originate from Somma-Vesuvius while some of them from Latium., Periodico di Mineralogia, Vol. 90 No. 1 (2021)

The ore deposits mined at Salafossa and Raibl (northeastern Italian Alps) were two of the largest Pb-Zn mineral deposits in Europe where the two metals were mainly present as sulphides (sphalerite and galena). Currently, the two mining districts are decomissioned and their galleries were partially flooded after the mine closure. In this context, water-rock interaction and the oxidation of sulphides are often responsible for increasing the mobility and dispersion of potentially toxic trace elements in the surrounding environment. Among minor constituents of sulphides, Tl is one of the most toxic elements and there is great concern regarding its occurrence, behaviour and fate in areas affected by both active and decommissioned mining activity. The geochemistry of the mine drainage waters was investigated at the two mining districts with the final aim of providing further information regarding their chemical composition, highlighting anomalous Tl and other trace element concentrations. In spite of the oxidation of sulphides which appears to occur, the buffering effect related to carbonate host rocks prevents the formation of acid mine drainage at both the investigated sites. Drainage waters were, however, found to be enriched in Zn, Pb and Tl (maximum of 16204, 80.1 and 261 µg L-1 at Salafossa and 5243, 70.1 and 80.1 µg L-1 at Raibl, respectively). Although drainage waters are diluted after being discharged into their respective riverine systems, Tl still remained at high levels in the freshwater downstream from the mines, especially at Raibl. There, the Tl-enriched groundwater flowing into the tailing ponds appears to affect the chemical composition of the freshwater of the Rio del Lago stream.