Native arsenic - realgar mineralization in marbles from Saualpe, Carinthia, Austria

The Geochemical Atlas of Austria shows a notable positive geochemical arsenic anomaly in stream sediments of the Saualpe, eastern Carinthia, Austria. Detailed investigation has shown that it is caused by an unusual kind of mineralization in brecciated marbles. The mineralization consists predominantly of native arsenic (often in small, stellate aggregates) and realgar (+/- minor orpiment). The As content may reach as much as 1.4 wt-%. The samples investigated do not contain any sulfarsenides and arsenides, and do not show enrichments of other metals: e.g. gold contents are <5 ppb, Hg contents less than or equal to 1.3 ppm, Sb contents less than or equal to 4 ppm. The atomic As/S ratio varies considerably, and surpasses in a number of samples a value of 2. The As mineralization seems to be associated with the formation of late, extremely fine-grained quartz +/- carbonate, penetrating the breccia, and is evidently a very late event in the mineralization history of the region.