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Porretta quartz sites, Porretta Terme, Alto Reno Terme, Reno Valley, Bologna Province, Emilia-Romagna, Italy

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Name(s) in local language(s):Siti del quarzo di Porretta, Porretta Terme, Alto Reno Terme, Valle del Reno, Provincia di Bologna, Emilia-Romagna, Italia
Location is approximate, estimate based on other nearby localities.
 
Latitude & Longitude (WGS84): 44° North , 10° East (est.)
Margin of Error:~1km
Köppen climate type:Cfb : Temperate oceanic climate


Quartz occurrences in the area around Porretta Terme in the so-called Porretta Sandstone (Arenarie di Porretta) or «Macigno di Porretta», presently referred to as Arenarie di Suviana, belonging to the terrigenous Miocene turbidite formations of the Tuscan Domain.

The Porretta sandstone is a dark grey-coloured, medium-grained lithic arkose, with white mica (muscovite) lamellae oriented parallel to the stratification planes. From a petrographic point of view, these rocks mainly consist of quartz, feldspars and phyllosilicate grains with a minor amount of siliciclastic rocks fragments. A certain amount of extrabasinal carbonatic clasts is also present. The carbonatic cement generally tends to occlude the interstices among grains.

The sandstone was extracted from different quarries located south and south-west of the Porretta Terme village (e.g. Madonna del Ponte, della Costa, Puzzola, and San Rocco quarries); some of these quarries are no more visible since they have been hidden by the new buildings of the thermal resort. This sandstone has been widely employed up to the last century in building works realized in the Porretta area such as the Madonna del Ponte church and along the Reno valley up to Bologna.

Lithoclases in sandstone, up to some decimetres in width, are characterised by the presence of calcite and quartz crystals. Quartz crystals tipically developed skeletal growth forms and show inclusions of light yellow-grey clay. Crystals frequently contain also water and gaseous hydrocarbon inclusions (Gambari, 1868; Bombicci, 1869 and 1874; Chamberlin, 1908; Mullis, 1988). These crystals have smooth and lustrous, in part curved faces and very often they form aggregates of two or more crystals. Several large crystal aggregates, one of which weighs more than 14 kg, were found to the south of Porretta Terme during the excavation of the Porrettana Railway tunnels (Bombicci, 1869).

Quartz crystals are found everywhere in rock clefts of the Arenarie di Suviana (Porretta Sandstone) formation, in the area located between Porretta Terme to the north and the border with Tuscany to the south, the church of Madonna del Ponte (right side of Reno River, municipal territory of Castel di Casio) to the east and Corno alle Scale (upper Silla stream valley, municipal territory of Lizzano in Belvedere) to the west. This area includes the top localities of Madonna del Ponte quarry (Castel di Casio municipality), della Costa quarry (former Porretta Terme municipality, now Alto Reno Terme), Porettana Railway tunnels and cuts between Porretta Terme and Pracchia (Pistoia Province, Tuscany), Rio Maggiore (former Porretta Terme and Granaglione municipalities, now Alto Reno Terme), Granaglione (former Granaglione municipality, now Alto Reno Terme).

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Standard Detailed Strunz Dana Chemical Elements

Mineral List

Mineral list contains entries from the region specified including sub-localities

2 valid minerals.

Detailed Mineral List:

Calcite
Formula: CaCO3
Reference: Jervis, G. (1874) I tesori sotterranei dell'Italia. Vol. 2: Regione dell’Appennino e vulcani attivi e spenti dipendentivi. Ermanno Loescher, Torino, XVIII+624 pp.; Bargossi, G.M., Gamberini, F., Gasparotto, G., Grillini, G.C., Marocchi, G. (2004) Dimension and ornamental stones from the Tosco-Romagnolo and Bolognese Apennine. Periodico di Mineralogia, 73, Special Issue 3, 171-195.
Quartz
Formula: SiO2
Reference: Gambari, L. (1868) Descrizione dei quarzi di Porretta. Atti della Società dei naturalisti e matematici di Modena, 3, 1-19; Bombicci, L. (1869) La collezione dei cristalli di quarzo aeroidro di Porretta. Memorie della R. Accademia delle Scienze dell'Istituto di Bologna, serie 2, 9, 56-60; Bombicci, L. (1874) Descrizione della mineralogia generale della provincia di Bologna. Seconda parte. Memorie della R. Accademia delle Scienze dell'Istituto di Bologna, serie 3, 5, 105-222; Jervis, G. (1874) I tesori sotterranei dell'Italia. Vol. 2: Regione dell’Appennino e vulcani attivi e spenti dipendentivi. Ermanno Loescher, Torino, XVIII+624 pp.; Chamberlin, R. T. (1908) The gases in rocks. Carnegie Institute of Washington, Publication 106, page 41; De Michele, V. (1974) Guida mineralogica d'Italia. Istituto Geografico De Agostini, Novara, 2 vol., 408 pp.; Mullis, J. (1988) Rapid subsidence and upthrusting in the Northern Apennines, deduced by fluid inclusion studies in quartz crystals from Poretta Terme. Schweizerische Mineralogische und Petrographische Mitteilung, 68, 157-170; Bargossi, G.M., Gamberini, F., Gasparotto, G., Grillini, G.C., Marocchi, G. (2004) Dimension and ornamental stones from the Tosco-Romagnolo and Bolognese Apennine. Periodico di Mineralogia, 73, Special Issue 3, 171-195; Castagliola, P., Cipriani, V., Pratesi, G., Niedermayr, G. (2006) Die 'Quarz-Diamanten' aus dem Apennin in Italien (Toskana und Emilia Romagna). Mineralien-Welt, 17, 2, 58-66.

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
'Quartz'4.DA.05SiO2
Group 5 - Nitrates and Carbonates
'Calcite'5.AB.05CaCO3

List of minerals arranged by Dana 8th Edition classification

Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2

List of minerals for each chemical element

CCarbon
C CalciteCaCO3
OOxygen
O CalciteCaCO3
O QuartzSiO2
SiSilicon
Si QuartzSiO2
CaCalcium
Ca CalciteCaCO3

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Gambari, L. (1868) Descrizione dei quarzi di Porretta. Atti della Società dei naturalisti e matematici di Modena, 3, 1-19.
Bombicci, L. (1869) La collezione dei cristalli di quarzo aeroidro di Porretta. Memorie della R. Accademia delle Scienze dell'Istituto di Bologna, serie 2, 9, 56-60.
Bombicci, L. (1874) Descrizione della mineralogia generale della provincia di Bologna. Seconda parte. Memorie della R. Accademia delle Scienze dell'Istituto di Bologna, serie 3, 5, 105-222.
Jervis, G. (1874) I tesori sotterranei dell'Italia. Vol. 2: Regione dell’Appennino e vulcani attivi e spenti dipendentivi. Ermanno Loescher, Torino, XVIII+624 pp.
Chamberlin, R. T. (1908) The gases in rocks. Carnegie Institute of Washington, Publication 106, page 41.
De Michele, V. (1974) Guida mineralogica d'Italia. Istituto Geografico De Agostini, Novara, 2 vol., 408 pp.
Mullis, J. (1988) Rapid subsidence and upthrusting in the Northern Apennines, deduced by fluid inclusion studies in quartz crystals from Poretta Terme. Schweizerische Mineralogische und Petrographische Mitteilung, 68, 157-170.
Bargossi, G.M., Gamberini, F., Gasparotto, G., Grillini, G.C., Marocchi, G. (2004) Dimension and ornamental stones from the Tosco-Romagnolo and Bolognese Apennine. Periodico di Mineralogia, 73, Special Issue 3, 171-195.
Castagliola, P., Cipriani, V., Pratesi, G., Niedermayr, G. (2006) Die 'Quarz-Diamanten' aus dem Apennin in Italien (Toskana und Emilia Romagna). Mineralien-Welt, 17, 2, 58-66.

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