Lower Scerscen Glacier, Scerscen Valley, Lanzada, Sondrio Province, Lombardy, Italyi

Regional Level Types
Lower Scerscen Glacier	Glacier
Scerscen Valley	Valley
Lanzada	Municipality
Sondrio Province	Province
Lombardy	Region
Italy	Country

Dolomite marbles and metaradiolarites, belonging to the sedimentary cover of the Margna nappe, in the area of Lower Scerscen Glacier.
Minerals are found in mineralised fissures in dolomite marbles (mainly along a belt between the elevation mark 3156 m and the proglacial lake impounded by the terminal moraine of the retreating glacier) and manganese-bearing mineralisation in metaradiolarites (along a belt between Pizzo Malenco and the glacier bottom). Numerous mineralised blocks are dispersed in the rock debris and moraines of the upper Scerscen Valley.

Crystalised minerals of the dolomite marble fissures include dolomite, calcite, rutile (acicular crystals up to 2 cm), apatite, fluorite, phengite, goyazite, hematite, and galena.

Components of the manganese mineralisation are rhodonite, spessartine, braunite, carbonates and various accessories. Anatase occurs as yellow tabular crystals in fissures inside quartz schist at the contact with the manganese mineralisation. Among the most interesting minerals of the manganese mineralisation: a Mn-bearing amphibole originally classified as "tirodite" (Bedognè et al, 1993; Stalder et al. 1998) and later as "manganocummingtonite" (Bedognè et al., 2006), as yellow or brown fibrous aggregates and flattened elongated crystals, often grouped in tufts up to 2 cm in length; pyrophanite, as yellow-brown plates and cherry-red to blood-red hexagonal tabular crystals, often grouped in rosettes up to 1 cm in diameter; tiragalloite, as orange to orange-red transparent wedge-like crystals up to several millimeters in length. It is interesting to remark that the first 4 mm-long tiragalloite crystals were found in an erratic block in 1956, but this mineral was correctly identified only in 1992 by Callegari et al.

Furthermore, dravite crystals are embedded in chlorite-rich quartz schist of the Margna nappe.


Note on the locality name:
some authors (for example Stalder et al, 1998) mention the Piz Scerscen south slope as the approximate locality of the Mn-bearing mineralisation, but this indication should be avoided because it is geographically incorrect. In fact, the Piz Scerscen south slope not only is situated 4.5-6 km NE of the actual outcrops but it also feeds a different glacier, the Upper Scerscen Glacier. The south-facing Upper Scerscen Glacier is bordered by Piz Sella (3506 m), Piz Roseg (3937 m), Piz Scerscen (3971 m), Piz Bernina south summit (4020 m), Cresta Guzza or Crest’Agüzza (3854 m), Piz Argent (3945 m), and Punta Quinto Alpini (3333 m). The east-facing Lower Scerscen Glacier is bordered by Sassa d’Entova (3329 m), Pizzo Malenco (3438 m), Pizzo Tremoggia (3441 m), Piz Glüschaint (3594 m), La Sella (3584 m), I Gemelli or Dschimels (3501 and 3497 m), and Pizzo Sella (3506 m). Once they have been joined, but now they are two separated glaciers.

Note on the Mn-bearing amphibole:
It was classified as “tirodite” (Bedognè et al., 1993) according to the amphibole nomenclature (Leake, 1978) in use at that time. Analyses showed the presence of Na, Fe, and Al. Later, according to a new amphibole nomenclature (Leake et al., 1997), the mineral was attributed to "manganocummingtonite" (Bedognè et al., 2006). After the institution of "parvowinchite" (Leake et al., 1997; Burke and Ferraris, 2003) it was supposed that the above-mentioned amphibole could be ascribed to this species, due to the presence of Na, Fe, and Al (although their amount in the empirical formula does not reach the minimum required threshold). A possible underestimation of the sodium content during the analyses has been inferred. In consequence of the last amphibole nomenclature (Hawthorne et al., 2012), in which the sodium-(magnesium-iron-manganese) amphibole (ex-“tirodite”) is named ferri-ghoseite, the Mn-bearing amphibole from Lower Scerscen Glacier has been tentatively ascribed to this species. New accurate analyses on both the fibrous facies and the idiomorphic crystals allowed to identify the orange mineral as a new species named clino-suenoite (Oberti et al., 2017).

06\07\2020 update: provided coordinates are still approximate (sort of centroid of collecting area), but at least now in the appropriate place.

Other Regions, Features and Areas containing this locality

References