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LocalitiesGroppera Alp, Madesimo, Sondrio Province, Lombardy, Italy

13th Nov 2013 12:22 UTCPaolo Giovanni Biffi

There is a bit of misleading information in the toponomastic for this locality (which therefore is of importance being a TL).

Indeed both Groppera Valley and Scalcoggia Valley (or better Scalcoggia Creek aka Madesimo Valley) are two distinct localities in the nearby of Madesimo being located the first about 0.7 Km ESE of the Madesimo citycenter and the second about 3 Km NNE of it.

Please find here a reference map

Therefore they are almost 4Km a part, with disconnected outcrops and partly different mineral assemblages, despite sharing the same hosting bedrocks; which could be enough to justify a subdivision of the two localities

The most relevant difference is the occurrence of abundant Pyrophillite at Scalcoggia Creek which was not found (so far and to my knowledge) at Groppera Alp

Then Lazulite from Scalcoggia is lighter in color and rarer with respect to the one from Groppera

To my knowledge and so far, Woodhouseite in yellowish to light orange rough crystals is the only other phospate associated with Lazulite at Scalcoggia.

Other phospates beside the one listed in mindat, were found at Groppera, a more comprhensive list should be in the reference here below.

I am sure that more details for both localities can be found in: Bedogné, F., Maurizio, R., Montrasio, A. & Sciesa, E. (1995): I Minerali Della Provincia Di Sondrio E Della Bregaglia Grigionese: Val Bregaglia, Val Masino, Val Codera E Valle Spluga. Bettini, Sondrio, Italia, 300 pp

My proposal is to eliminate any refererence to Scalcoggia (Valley or Creek) from the toponomastic of the locality Groppera Alp and eventually to create a new locality for the mineralised outcrops of Scalcoggia.

Concerning photos: the three mineral photos currently on mindat do belong to Groppera Alp, whilst the site photo is from Scalcoggia as correctly indicated in the commentary phrase.

Cheers

Paolo

14th Oct 2015 17:48 UTCPaolo Giovanni Biffi

An addendum:

In my opinion the mineral Kyanite has been added without any valid justification or by mistake.

Because:

1) the reported bibliographic reference "(Brugger J. (1996): The Fe, Mn, (V, Sb, As, Be, W) deposits of Val Ferrera (Graubünden, Switzerland). Unpublished PhD Thesis, Univ. Basel. 188 p." has nothing to do neither with the locality nor with the paragenesis in question.

2) I personally surveyed both Alpe Groppera and Torrente Scalcoggia collecting sites several times since their discovery in 1984, never observing any trace of kyanite, especially in macroscopic samples.

3) the posphates are hosted both in quartz rich layers and in mica rich layers of what appears to be a "low (green schists ?) metamorphic grade" meta-pelite \ meta-psammite interpreted to be part of the oldest (permo-triassic ??) sedimentary cover of the Suretta Nappe. Although not impossible the occurrence of Kyanite in such contest would be unsual, In addition the occurrence of pyrofillite at Torrente Scalcoggia is not in favour of the co-occurence of Kyanite (pyrophillite is replaced by Kyanite (or Andalusite) + Quartz at temperature higher than about 400°C.

I am not saying that is impossible to found some Kyanite, even in macroscopic samples not far from the described sites. That's because rock masses belonging to the "hercinian basement" outcrop not far from both sites.

....But not in association with the phospate bearing rocks here described.

Please remove Kyanite and the related biblio reference.

Paolo

14th Oct 2015 18:20 UTCPaolo Giovanni Biffi

added one Google Earth aerial view of the Alp Groppera collecting Area

P.

14th Oct 2015 18:29 UTCPaolo Giovanni Biffi

http://www.mindat.org/photo-710964.html

27th Oct 2015 13:41 UTCReiner Mielke Expert

Kyanite changed to erroneously reported.

29th Oct 2015 09:40 UTCPaolo Giovanni Biffi

Thanks Reiner

Paolo

29th Oct 2015 10:42 UTCPaolo Giovanni Biffi

Added Scalcoggia Creek as new sublocality under "Madesimo"

Removed any reference to Scalcoggia from "Alp Groppera" locality

in order to certify that indeed there are two different phosphate bearing localities close to Madesimo

Added Pyrophillite & Lazulite to "Scalcoggia" locality

all is awaiting for approval

Paolo

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