Quartz occurrences, Gabbro, Rosignano Marittimo, Livorno Province, Tuscany, Italyi

Regional Level Types
Quartz occurrences	Group of Occurrences
Gabbro	Village
Rosignano Marittimo	Municipality
Livorno Province	Province
Tuscany	Region
Italy	- not defined -

In the town of Gabbro, in the area of ​​the old wash houses, there are interesting quartz mineralizations and other mineralogical species.
They are found at the stratigraphic base of the neo-autochthonous sediments, near the contact with the underlying serpentine rocks. Their origin could be linked to the underground circulation of the same fluids that gave rise in the serpentinites to the extensive mineralizations of magnesite, dolomite and chalcedony that very widely affect the territory of the municipality of Rosignano Marittimo.

A first report of these mineralizations dating back to 1988 concerns the presence of quartz, chalcedony, opal and magnesite in small geodes in the layers of the sandstone formation of the Sanguigna stream.
The place of discovery is located on the eastern side of the hill on the top of which Villa Mirabella was erected.

Recent and extensive inspections conducted in the area have not shown even the slightest trace of this mineralization; people who have visited this place in the past years claim that it is a tiny outcrop, nowadays affected by a landslide and by weeds that have obliterated the vision.

Not far from the previous location, a mineralization of quartz and chalcedony has been found which has not yet been reported in the literature and therefore described for the first time here.

These are geodes of even decimetric dimensions, entirely covered with quartz as colourless or whitish crystals of variable dimensions but in any case not exceeding a few millimetres, with the prism very little or not at all developed.

The peculiarity of this mineralization is constituted by the fact that in some geodes there are two different generations of quartz.

The first generation is made up of druses with a mammillary appearance of generally colourless crystals, directly implanted on the rock.

The second is formed by a kind of crust with a thickness of a few millimetres, located above the first generation of quartz, consisting of a veil of chalcedony and crystals of quartz similar to the previous ones but whitish in colour and not very transparent. This crust is perfectly modelled on the underlying mineralization while being able to detach itself quite easily.

The mineralized rock is made up of decimetric layers of fine-grained grey limestone, fetid on percussion, very compact, completely pervaded by geodes carpeted with quartz.

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