Sasso di S. Zanobi
An age-old rock formation between legend and geology in the upper Valle del Diaterna
The Rock Formation
A fragment of ancient oceanic crust, surfacing among the mountains of the Mugello
The Sasso di San Zanobi — called Sasso di San Zenobi in Emilia-Romagna — is an extraordinary rock formation rising in the Tuscan-Romagnol Apennines, in the valley of the Diaterna stream, a short distance from the Raticosa Pass, in the Caburaccia area of the municipality of Firenzuola.
Geologically, the Sasso is an ophiolite: a fragment of ancient oceanic crust which, instead of being subducted, was thrust over a continental margin during the tectonic movements that shaped the Apennines. Its partly metamorphosed basaltic composition is responsible for the characteristic greenish and violet streaks running through the rock — shades produced by metamorphic minerals such as serpentine and talc. Those same streaks earned the area its medieval name of Pietramora, for the dark colour that sets the rock apart from the surrounding landscape.
Two other ophiolites lie nearby: the Sasso della Mantesca (or Devil's Rock), with blue and white glints, in the neighbouring Sillaro valley, and the Sasso delle Macine. Together these three formations are among the rarest and most striking geological features of the northern Apennines.
The Sasso stands at about 966 metres, clearly visible from the valley floor for its distinctive triangular shape and the dark colour that sets it sharply apart from the surrounding Cretaceous terrain. A small chapel of San Zanobi also stood here, recorded in the tithe book of 1299 and destroyed during the Second World War fighting that heavily affected this stretch of the Apennines.
The Legend
The bishop, the devil and the contest that gave the rock its name
In the fourth century, Bishop Saint Ambrose of Milan met the bishop of Florence, Saint Zanobi, near Malomonte, where the latter was engaged in his evangelising work. After that meeting, Saint Zanobi felt his strength double and won new conversions in the area between the Diaterna, Caburaccia and the Idice.
This wave of faith stirred the devil's wrath: he summoned an infernal council and challenged the bishop — whoever could carry the largest boulder from the Idice to the top of the hill would win the souls of every inhabitant of the place. Saint Zanobi accepted, entrusting himself to God.
The devil took up an enormous boulder and toiled his way towards the summit. Saint Zanobi, sustained by faith, chose an even larger rock and carried it lightly on his little finger, overtaking the devil and setting the stone down where it still stands today. Seeing himself beaten, the demon flew into a rage and hurled his boulder, which shattered amid fire and flames: this is the Sasso della Mantesca, broken and restless in its glints, in the nearby Sillaro valley.
The legend is still alive in the local community. On the first Sunday in July the Feast of San Zanobi is celebrated: from the hamlet of Caburaccia a procession carries the saint's statue to the foot of the Sasso, where a preacher reads the praises of the patron bishop. A tradition handed down for generations, weaving together popular devotion and the memory of this remote corner of the Apennines.
The Sasso di San Zanobi appears at the beginning of Daniele Luchetti's film La settimana della Sfinge (1990) and was filmed during the RAI programme Easy Driver in 2011.
How to Get There
The Sasso di San Zanobi is easily reached from the provincial road running from Firenzuola to Piancaldoli, near the Passo della Raticosa.
The rock is reached on foot from the hamlet of Caburaccia, along a short ridge path. There is a parking area nearby. The walk is easy, suitable for hikers of any level, and already on the way up it offers sweeping views over the upper Valle del Diaterna and, on clear days, as far as the Adriatic.
The local paths are part of the hiking network of the CAI — Italian Alpine Club and carry the usual red-and-white waymarks. For up-to-date route information see the Trails section of this site.