Allori Mine (Allori Pit; Allori deposit), Cavriglia, Arezzo Province, Tuscany, Italyi

Regional Level Types
Allori Mine (Allori Pit; Allori deposit)	Open-Cast Mine
Cavriglia	Commune
Arezzo Province	Province
Tuscany	Region
Italy	- not defined -

Open-pit mine of the Santa Barbara mining concession, situated near Bomba locality, operated in the homonymous lignite deposit in the period 1974-1992. It reached the depth of 150 m. Presently reclaimed. The Allori deposit was previously mined mainly by underground methods (Innocenti or San Martino and Allori mines). The presence of oucropping xyloid lignite in the place known as Pian Franzese or Pian Francese near the former hamlet of San Martino (destroyed by the recent mining workings) was first reported by Giuli (1843).

The recent open-pit mining operations allowed to discover layered deposits of phosphates inside the Meleto Clays. Anapaite and vivianite were abundantly found, but always separately in different layers.
Anapaite occurs as radiating masses with variable shape and size. The interior contains many cavities filled by aggregates of triclinic tabular crystals. The crystals are green or yellow-green, translucent, vitreous, and a millimeter or two in size. A gradual change in the character of the masses, with regard to their position inside Meleto Clays, has been observed: in the uppermost part there are small nodules, nearly spherical and about 1 cm in diameter, progressing to nodules as large as 10 cm in diameter in the lower part. The anapaite nodules often appear joined together to form a compound cluster. At the bottom of the formation of Meleto Clays, near the Macigno Sandstone, layers of anapaite with a thickness ranging from 5 to 20 cm and an extension of tens of meters occur.
Vivianite, besides the typical dark blue earthy concretions and radiating nodules to some centimetres across or as a replacement of vegetable organic matter, was found in 1990 as thin layers interbedded with clays. These same bluish clays have also yielded some spectacular specimens embedded in them, consisting of grenish-blue to bluish-green plates covered with crystals more than 10 cm in length and radiating crystal aggregates up to 20 cm in length.

Gypsum, as aggregates of greyish dull prismatic crystals, has been occasionally found in the bluish clays. However, the best specimens, consisting of colourless elongated crystals reaching several centimetres in length, have been found on a particular orange-red brick-like matrix, which formed during lignite self-combustion through clay baking and the consequent oxidation of ferrous minerals (Billi, 1980; Brizzi et al., 1991; Corazza et al., 1994). According to the field observations of Lotti (1897), this red brick-like matrix was particularly abundant in the Allori area.

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References