n. 533 / May 2006

 

 

Southern Piedmont in the past saw intense quarrying activity of carbonatic rocks. In particular, Monregalese (Morozzo della Rocca, 1972) - that is, the region corresponding to the ancient province of Mondovì - was a quarry area with dozens of quarries that produced many varieties of marble, both white and - especially - coloured (Peretti 1937 and 1938). The borders of the Monregalese area are defined with exactness but roughly extended between the valleys of the Pesio Torrent and the River Tanaro and included the Ellero, Corsaglia, Casotto and Mongia Torrents. This area of Piedmont saw the exploitation of important decorative stones, especially “marbles”, and - to a lesser extent - sandstones (Vicoforte Stone). Local building materials also included many other lithotypes, such as gneiss and quartzites: in particular, fissile rocks were used for roofs and flooring slabs (Various Authors, 2005; Fiora et al., 2001).

 

Carbonatic rocks (marbles) were in great demand and in some cases were even exploited during the Roman Age (for example, Frabosa marbles and Brossasco marble, Frisa Morandini & Gomez Serito, 1998). In the 1600s and, especially, the 1700s many were used as prized decorative materials in the churches and palaces of Piedmont. Some varieties, on the other hand, came to the fore in the 1800s and 1900s.

 

From a geological point of view (Lombardo, 2002; Various authors, 2005 with bibliography), the marbles of Monregalese date from the Triassic (dolomies and dolomitic limestones from the San Pietro dei Monti Dolomie Formation), Jurassic (dark limestones, conglomerates, almond pink limestones) and Eocene (limestones and dolomitic breccias) periods. Petrographically speaking, most of these rocks underwent low to very-low metamorphism.

 

Found mostly in small outcrops, they were often worked through to total exhaustion. Exploitation continued through to our own times in very few cases, while resumption of quarrying with limited production may be possible. The are 51 varieties, from about 40 quarries - in some cases working individual boulder quarries (Badino & Frisa, 1992; Cavarero, 1996). Although pure white marbles are found, most varieties have grey, black, pink, red, yellow and green colours, as well as a few multi-colour types. Grey/black colourng is associated with the presence of carbon substances, pink and red with haematite, yellow from goethite, violet from the presence of manganese, as well as iron, while green mostly derives from chlorite (Pieri, 1957). The patterning of these rocks ranges from uniform to veined (Portoro type); a breccia pattern is sometimes seen. The pink and red varieties were once very popular (Gilibert, 1992).

 

The Tanaro Valley provided statuary white, black and Portoro type veined marbles and several coloured varieties, such as pink stones, Gridellini (pink/lilac) and Persichini or Persighini (pink/red) materials. The Casotto Valley was worked to supply the famous Casotto Breccia and Persichini/Gridellini materials, including a variety known as Fior di Pesco. The Corsaglia Valley is an excellent valley marble, with different varieties of marble: white (Frabosa), verzino (Frabosa and Ruata), grey (Frabosa and Moncervetto), black (Frabosa, Vallone or Ormea, Miroglio), yellow (Frabosa), violet (Piedmont or Moncervetto) and red (Piedmont or Val Corsaglia), as well a breccia-like varieties (Serravezza or Saravezza Moncervetto).

 

Outside the Monregalese region but still in southern Piedmont and the present-day province of Cuneo, the marbles of Valle Gesso enjoyed some historic importance - that is, Valdieri marbles in white, bardiglio, cipollino dorato and green cipollino varieties; these low metamorphic rocks were the sedimentary coverage of the Argentera Massif (Lombardo, 2002). Quarrying activity for bardiglio began in 1743, as recalled in an engraving in the quarrying area itself; the quarry then became the property of the King. Cipollino was extensively used abroad (London Town Hall, Bangkok Royal Palace, the Italian Circle in Buenos Aires, Government House in Havana; Peretti, 1938). Stura di Demonte Valley saw quarry work on the Moiola marbles, including the famous Serravezza stone, while Vermenagna Valley produced Lemon Serravezza or Pavonazzetto. Other important marbles from the Cuneo area were Brossasco white marble in Varaita Valley, green Acceglio marble (an ophicarbonatic rock) in Maira Valley and the so-called Busca Onyx alabastrine.