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

Etruscan and Roman metallurgicalslags, tens of meters thick in some places, extend to the coastline in the Gulf of Baratti. Theslags altered by seawater reveal many interesting Pb-Cualteration 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/].

Baratti plain, near the ancient town ofPopulonia (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 ofiron andbase metal resources from nearbyElba Island andCampiglieseore 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 ofiron 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 ofiron slag were exploited for re-smelting in modernblast furnaces. The recovery of ancientslags 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 originalstratigraphy of archaeological layers and destroyed most evidence (e.g.furnaces) of metalworking activity.

The remains of theslagdeposit, a poorly cemented heap of Etruscan and Romanslags discharged over an erosionalterrace, is observable just above the beach. Although theslagdeposit 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 originalstratigraphy after the exploitation taking place during the past century. Thedeposit is constituted bylayers of variable length and thickness, which usually contain different quantities ofslags,charcoal, and stone fragments. It can be reasonably argued that they represent a sequence resulting from the discharge of metallurgical wastes. Thedeposit can be described as constituted by an upper portion characterised byiron slags, and a lower sequence containing variable amounts ofcopperslags, clearly identifiable by the greenish spots (due toexogeneticalteration ofcopper sulphides) on their surfaces.

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

Type-Acopperslags are characterised by a groundmass of dominantolivine,pyroxene,magnetite, and minorglass, with abundant metallic droplets, mostly fine aggregates of metalliccopper,copperoxides (cuprite) andcopper sulphides (covellite,chalcocite/digenite).

In type-Bcopperslags,magnetite andcuprite are much less abundant, metalliccopper is consistently absent, and the metallic globules (100-150 μm in size) are mainlycopper-iron-sulphur phases (matte) showing fineexsolutiontextures. These features could indicate a multi-stagecoppersmelting process, with type-Bslags belonging to an earlier (matte production) stage than type-Aslags.

The largest portion of theslagdeposit consists ofiron slags of different kinds (furnaceslags, tappedslags,furnaceconglomerates). Theiron slags are mainly asilicate ground mass of fayaliticolivine (with up to 1.45% CaO) in an iron-rich interstitialglassy matrix (up to circa 25 wt.% FeO), which in itself is normally aeutectic ofanorthite andfayalite.Wüstite,magnetite,hercynite and partially smelted, relic phases likequartz,hematite,scheelite, andilmenite, occur in variable amounts and are especially abundant infurnaceslags.Fayalite crystals in tappedslags occur as small laths associated with micrometricdendrites ofwüstite, while infurnaceslags both minerals show a significant increase in size. Unlike tapped andfurnaceslags,furnaceconglomerates show abundant relics ofhematite andquartz and a more silica-rich (and FeO-poor)glassy ground mass.Iron slags almost invariably contain droplets of metalliciron. Someiron slags are enriched intin and may contain micrometric globules ofiron-tinalloys, approximating FeSn and FeSn2 in composition.

Fragments ofsmeltingfurnaces are also commonly present in the Baratti beachdeposit. They are made up of local Macignosandstone and bakedclay. The bakedclays show characteristic colour zoning from red to black, corresponding to increasing reducing atmosphere and temperatures in thefurnaces.

Note on the mineral list: A natural phase with chemical formula Pb2Fe3+Cl3(OH)4·H2O (Pasero et al., 1997) (Unnamed (Pb-Fe Chloride Hydroxide Hydrate)) was sampled on the Baratti beach. The proposal of 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 was 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).

Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Baratti_(town)
Wikidata ID:	Q1172685

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References