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Isola Quarry (Isola Quarries), Isola, Madesimo, Spluga Valley (San Giacomo Valley), Valchiavenna, Sondrio Province, Lombardy, Italy

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Latitude & Longitude (WGS84): 46° 26' 56'' North , 9° 20' 31'' East
Latitude & Longitude (decimal): 46.44889,9.34222
Name(s) in local language(s):Cava di Isola (Cave di Isola), Isola, Madesimo, Valle Spluga (Valle San Giacomo), Valchiavenna, Sondrio, Lombardia, Italia
Other regions containing this locality:The Alps, Europe

Near Isola di Madesimo, on the left side of River Liro, a dimension stone, commercially called "Quarzite verde dello Spluga" or simply "Verde Spluga", is extracted from long time. It is a fine-grained rock with light green colour and with shades varying according to the percentage content of various minerals. A fengite porphyroid (the most valuable) and a schistous facies are present. The rock is used in buildings and also for ornamental purposes, due to its aesthetic characteristics.

Historically, in this area, two indipendent quarries operated: at both northern and southern quarries the original open-air quarrying was substituted by underground extraction. The northern quarry is now inactive, while underground quarrying is still intensively performed at the southern one, thanks to the considerable thickness of the vein (up to 40 m).

Fissures in porphyroid rocks can contain various crystallised minerals: quartz (hyalin and smoky crystals), albite, muscovite, pyrite, rutile var. sagenite, dolomite, hematite, aragonite, scolecite, dravite, anatase, brookite, apatite, and calcite.

Mineral List

12 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on

Cretaceous - Permian
66 - 298.9 Ma
Metamorphe Gesteine, meist Metasedimente

Age: Phanerozoic (66 - 298.9 Ma)

Lithology: Metamorphic rocks, mostly metasedimentary

Reference: Geological Institute. Geological Map of Switzerland 1:500,000. isbn: 3906723399. University of Bern. [49]

Data and map coding provided by, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


- Buzzetti P. (1928): Il passo dello Spluga e strade valchiavennasche". Tip. A. Volta di S. A. Caccia e C., Como, 45 pp.
- Bundi M. (1969): La storia del passo dello Spluga. Rassegna economica della Provincia di Sondrio, n. 7-8, 22-33.
- Bundi M. (1970): La storia del passo dello Spluga. Quaderni grigionitaliani, 39, 1, 9-26.
- Planta T. (1993): Le antiche strade dello Spluga. Centro Studi Valchiavennaschi, Collana Quaderni Centro Studi Storici Valchiavennaschi, Chiavenna, 116 pp.
- Fedele F. (1994): Preistoria e paleoambienti della Valchiavenna 1994: S. Caterina di Gordona, Pian dei Cavalli, Montespluga. Clavenna, XXXIII, 9-86.
- Benetti D. (1995): Abitare la montagna – Tipologie abitative ed esempi di industria rurale. In: Lurati O., Meazza R., Stella A. (eds.), Mondo popolare in Lombardia, n. 15, Sondrio e il suo territorio. Silvana Editoriale, Milano, pages 41-92.
- Bedognè F., 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, 300 pp.
- Bedognè F., Montrasio A., Sciesa E. (2006): I minerali della media-alta Valtellina, delle Orobie valtellinesi e della Val Poschiavo. Aggiornamenti sulle altre località della provincia di Sondrio. Bettini, Sondrio, 255 pp.

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