Baratti slag locality, Piombino, Livorno Province, Tuscany, Italyi

Regional Level Types
Baratti slag locality	Slag Locality
Piombino	Commune
Livorno Province	Province
Tuscany	Region
Italy	Country

This page is currently not sponsored. Click here to sponsor this page.

PhotosMapsSearch

Etruscan and Roman metallurgical slags, tens of metres thick in some places, extend to the coastline in the Gulf of Baratti. The slags altered by seawater reveal many interesting Pb-Cu alteration minerals, similar to the Lavrion (Greece) ones.

Collecting is now strictly prohibited because the area has been included in the Archaeological Park of Baratti and Populonia (part of the Parks of Val di Cornia) [https://www.parchivaldicornia.it/en/natural-parks/sterpaia-coastal-park/].

The Baratti plain, near the ancient town of Populonia (Fufluna in Etruscan), was one of the most important metalworking sites in the Mediterranean region in the 1st millennium BC. Due to the large availability of iron and base metal resources from nearby Elba Island and Campigliese ore districts, Populonia became one of the most influential towns of Etruria during the period between the 6th century BC and the 1st century AD. As a testimony of the long-lasting metallurgical activity, heaps of iron slag and other metallurgical debris have been discharged over an area of about 220,000 m² (D’Achiardi, 1929) along the Gulf of Baratti, lying northeast of Populonia.

Starting from the end of World War I and up to the 1960s, tonnes of iron slag were exploited for re-smelting in modern blast furnaces. The recovery of ancient slags led to the discovery of the Populonia necropolis (Il Casone and Podere San Cerbone burial sites) and industrial site (La Porcareccia-Campo VI area) in the Baratti plain but also profoundly upset the original stratigraphy of archaeological layers and destroyed most evidence (e.g., furnaces) of metalworking activity.

The remains of the slag deposit, a poorly cemented heap of Etruscan and Roman slags discharged over an erosional terrace, are observable just above the beach. Although the slag deposit may be followed for about 200 m along the Baratti beach, only a small portion of it (about 30 m long), located close to the San Cerbone chapel, still maintains its original stratigraphy after the exploitation taking place during the past century. The deposit is constituted by layers of variable length and thickness, which usually contain different quantities of slag, charcoal, and stone fragments. It can be reasonably argued that they represent a sequence resulting from the discharge of metallurgical wastes. The deposit can be described as constituted by an upper portion characterised by iron slags and a lower sequence containing variable amounts of copper slags, clearly identifiable by the greenish spots (due to exogenetic alteration of copper sulphides) on their surfaces.

According to Benvenuti et al. (2000) and Chiarantini et al. (2009), analyses of the Baratti beach slag deposit led to the recognition of two main types of copper slags: type-A and type-B slags.

Type-A copper slags are characterised by a groundmass of dominant olivine, pyroxene, magnetite, and minor glass with abundant metallic droplets, mostly fine aggregates of metallic copper, copper oxides (cuprite), and copper sulphides (covellite and chalcocite/digenite).

In type-B copper slags, magnetite and cuprite are much less abundant, metallic copper is consistently absent, and the metallic globules (100-150 μm in size) are mainly copper-iron-sulphur phases (matte) showing fine exsolution textures. These features could indicate a multi-stage copper smelting process, with type-B slags belonging to an earlier (matte production) stage than type-A slags.

The largest portion of the slag deposit consists of iron slags of different kinds (furnace slags, tapped slags, and furnace conglomerates). The iron slags are mainly a silicate ground mass of fayalitic olivine (with up to 1.45% CaO) in an iron-rich interstitial glassy matrix (up to circa 25 wt.% FeO), which in itself is normally a eutectic of anorthite and fayalite. Wüstite, magnetite, hercynite, and partially smelted relic phases like quartz, hematite, scheelite, and ilmenite occur in variable amounts and are especially abundant in furnace slags. Fayalite crystals in tapped slags occur as small laths associated with micrometric dendrites of wüstite, while in furnace slags, both minerals show a significant increase in size. Unlike tapped and furnace slags, furnace conglomerates show abundant relics of hematite and quartz and a more silica-rich (and FeO-poor) glassy groundmass. Iron slags almost invariably contain droplets of metallic iron. Some iron slags are enriched in tin and may contain micrometric globules of iron-tin alloys, approximating FeSn and FeSn₂ in composition.

Fragments of smelting furnaces are also commonly present in the Baratti beach deposit. They are made up of local Macigno sandstone and baked clay. The baked clays show characteristic colour zoning from red to black, corresponding to increasing reducing atmospheres and temperatures in the furnaces.

Note on the mineral list: A natural phase with the chemical formula Pb₂Fe³⁺Cl₃(OH)₄·H₂O (Pasero et al., 1997) (Unnamed (Pb-Fe Chloride Hydroxide Hydrate)) was sampled by Marco Bonifazi on the Baratti beach. The proposal of the definition of the new mineral was rejected by the IMA CNMMN due to its anthropogenic origin. Therefore, the phase, which has the acronym PFC due to the chemical formula, cannot be considered a mineral species. However, we think it is useful to at least mention that phase here since it could have been another Italian type mineral if only it had been discovered a few times before. In fact, the definition of the nature of anthropogenic material and the relevant guidelines were set up by CNMMN in 1995 (Nickel, 1995). Collectors know the phase as "barattiite" ("barattite" is a synonym).

Mineral List

101 valid minerals.

Rock Types Recorded