Alpe Valley, Gavia Valley, Valfurva, Sondrio Province, Lombardy, Italyi

Regional Level Types
Alpe Valley	Valley
Gavia Valley	Valley
Valfurva	Municipality
Sondrio Province	Province
Lombardy	Region
Italy	Country

Realgar vein (up to 40 cm in thickness and more than 6 m in length) hosted in a quartz breccia horizon embedded in calcite marble.
This vein, which crops out in the upper Alpe Valley at an elevation of 2630 m, was discovered by R. Potenza in 1969 during a field survey of the area (Bianchi Potenza et al., 1981). Ravagnani and Tabacchi (1974) and other later authors roughly indicated this occurrence with the improper name of Gavia Pass (Passo di Gavia).

The mineralisation partly impregnates quartz breccia, partly forms a vein almost completely consisting of realgar with stibnite at the selvages. In the voids of the embedding breccia realgar appears as dull stocky prismatic crystals with rough faces; it is often associated with powdery or lamellar pararealgar, that at the time of its determination was a new mineral for Italy and Europe (Bianchi Potenza et al., 1981). At the vein selvages, stibnite appears as bacillar aggregates and also as acicular crystals, which are disseminated among quartz crystals in rock cavities, sometimes filled with spathic calcite. Realgar and stibnite alteration minerals are interesting and include valentinite, metastibnite, stibiconite, pharmacosiderite, and As-bearing amorphous phases. Pyrite, arsenopyrite, aragonite, graphite, anatase (tiny sapphire-blue dipyramidal crystals), and scheelite (white vitreous dipyramidal crystals) have also been observed.
Furthermore, at the entrance of an old military gallery, located about 100 m west of the realgar vein, realgar is found as unusual spherules and platelets included in hyaline quartz crystals, which in association with dolomite crystals line the walls of marble fissures.

More recently (about in 2012) centimetric rosettes of stibnite were found at an outcrop approximately 100 meter west of the Realgar outcrop.

Other Regions, Features and Areas containing this locality

References