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Ruin del Bo, Cima Pal (Cima di Pal), Castelnuovo Nigra, Metropolitan City of Turin, Piedmont, Italyi
| Regional Level Types | |
|---|---|
| Ruin del Bo | - not defined - |
| Cima Pal (Cima di Pal) | Mountain |
| Castelnuovo Nigra | Commune |
| Metropolitan City of Turin | Metropolitan City |
| Piedmont | Region |
| Italy | Country |
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Latitude & Longitude (WGS84):
45° 29' 40'' North , 7° 38' 44'' East
Latitude & Longitude (decimal):
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Frassinetto | 141 (2014) | 6.9km |
| Castelnuovo Nigra | 125 (2014) | 7.3km |
| Ronco Canavese | 177 (2014) | 7.7km |
| Cintano | 122 (2014) | 8.1km |
| Traversella | 212 (2014) | 8.2km |
Other Languages:
Italian:
Ruin del Bo, Città metropolitana di Torino (Provincia di Torino), Piemonte, Italia
Randomly oriented phengite flakes, up to 25 cm across and 5 cm thick, in a metamorphic dyke (Sesia-Lanzo zone) near the hut named Ruin del Bo (see ccordinates), on the E slope of Cima Pal (or Cima di Pal), upper Savenca Valley. This mica occurrece was mined during World War II.
Phengite formed at quartz-eclogite-facies conditions in the presence of hydrous fluid. A greenschist-facies retrogression locally altered the eclogite-facies assemblage.
The mica flakes show yellowish and greenish zoning, well visible if observed against the light. This colour zoning is superposed by a structural zoning of 3T and 2M1 (more abundant) polytypes. Tetrahedral cation order is absent in both polytypes, although partial octahedral order is present in the 3T polytype. Colour zoning is connected with differences in chemical compositions. Analyses performed on both polytypes showed the following results:
(K0.90Na0.05)(Al1.51Mg0.32Fe0.18Ti0.03)(Si3.40Al0.60O10](OH)2 [yellowish 3T polytype],
(K0.95Na0.01)(Al1.40Mg0.34Fe0.27Ti0.03)(Si3.50Al0.50O10](OH)2 [greenish 3T polytype],
(K0.98Na0.02)(Al1.55Mg0.24Fe0.21Ti0.02)[Si3.38Al0.62O10](OH)2 [yellowish 2M1 polytype],
(K0.99Na0.02)(Al1.42Mg0.33Fe0.24Ti0.04)[Si3.45Al0.55O10](OH)2 [greenish 2M1 polytype].
Colour and limited chemical zoning is attributed to a fluctuation in the fluid-phase composition. The 2M1 polytype with disordered pattern of octahedral cations was probably crystallised from the pre-existing 3T polytype by a solid state reaction. The transformation occurred during the sharp decompression stage leading to the greenschist facies, which triggered nucleation and growth of the 2M1 polytype (Ivaldi et al., 2001).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 9 - Silicates | |||
|---|---|---|---|
| ⓘ | Muscovite | 9.EC.15 | KAl2(AlSi3O10)(OH)2 |
| ⓘ | var. Phengite | 9.EC.15 | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
List of minerals for each chemical element
| H | Hydrogen | |
|---|---|---|
| H | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| H | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| O | Oxygen | |
| O | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| O | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Mg | Magnesium | |
| Mg | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Al | Aluminium | |
| Al | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| Al | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Si | Silicon | |
| Si | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| Si | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| K | Potassium | |
| K | ⓘ Muscovite | KAl2(AlSi3O10)(OH)2 |
| K | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
| Fe | Iron | |
| Fe | ⓘ Muscovite var. Phengite | KAl1.5(Mg,Fe)0.5(Al0.5Si3.5O10)(OH)2 |
Other Regions, Features and Areas containing this locality
Eurasian PlateTectonic Plate
- AlpsAccretionary Complex
EuropeContinent
- The AlpsMountain Range
Italy
- Piedmont
- Metropolitan City of Turin
- ⭔CanaveseDistrict
- Chiusella ValleyValley
- Savenca ValleyValley
- Metropolitan City of Turin
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References
Ivaldi, Gabriella, Ferraris, Giovanni, Curetti, Nadia, Compagnoni, Roberto (2001) Coexisting 3T and 2M1 polytypes of phengite from Cima Pal (Val Savenca, western Alps): Chemical and polytypic zoning and structural characterisation. European Journal of Mineralogy, 13 (6) 1025-1034 doi:10.1127/0935-1221/2001/0013-1025
Pavese, Alessandro; Curetti, Nadia; Ferraris, Giovanni; Ivaldi, Gabriella; Russo, Umberto; Ibberson, Richard (2003) Deprotonation and order-disorder reactions as a function of temperature in a phengite 3T (Cima Pal, western Alps) by neutron diffraction and Mossbauer spectroscopy. European Journal of Mineralogy, 15 (2). 357-363 doi:10.1127/0935-1221/2003/0015-0357
