Serpentinite

This metamorphic rock belonging to the ophiolite group, with its green, snakeskin colour (its name derives from the Greek word ofios, referring, indeed, to these greenish-coloured reptiles), is believed to have given its name to this series of geological formations, ancient sections of oceanic crust and mantle transposed onto continental areas during orogenesis.

Serpentinite, appearing in various shades of lighter and darker green and featuring fibrous, solid and crystalline structures, is formed by metamorphism of peridotites and composed mainly of magnesium silicates. On Elba, it can be found in various areas, particularly in the centre and east (Portoferraio, Le Grotte, Schiopparello, Golfo Stella and Monte Fico) but also in the western part of the island, which we are crossing as we walk the Via dell'Essenza. Here, large sections have been transformed into olivenites and amphibiolites through thermal metamorphism caused by the rise of the Mount Capanne pluton.

In Tuscany, serpentinite is commonly referred to as 'green marble' and has been used in many architectural constructions, particularly in the Tuscan Romanesque style, creating the characteristic green and white two-colour effect. On Elba, serpentinite was used to create the two-colour effect of the walls in the majestic Roman villa in Le Grotte. On the eastern side (eastern slopes of Mount Serra), there is a serpentinite particularly rich in calcite (ophicarbonate or ophicalcite) known as marmo di Santa Caterina ('marble of Santa Caterina') and also mentioned by the naturalist Ermenegildo Pini (1777) as marmo mischio ('multicoloured marble'), white veined with blackish-green.

Indeed, just above the Hermitage of Santa Caterina, there was once a quarry where this type of stone was extracted, used for ornamental purposes and to make the altars in the churches of Santa Caterina and Rio nell'Elba. 'Santa Caterina marble' was also used to create the floor of the Demidoff museum in San Martino, Napoleon's country residence.

(Antonello Marchese, translation from Italian)