1Producing salt in ancient times was a major, though often underestimated, activity. It has often been stressed that salt is both a biological necessity for human and animal health, and very important for the preservation of foodstuffs; it also has various uses in industry and in rural medicine. The problem for the archaeologist is that salt is invisible archaeologically, at least as a consumed material, since it is soluble and rarely survives the passage of time. Only a couple of certain examples of surviving archaeological salt are known to me: from the Ourania cave near Zakros on Crete came a number of small pieces of salt, weighing around 500 g in total, mixed in with potsherds that apparently formed the container (Kopaka, Chaniotakis 2003); and most recently a small piece of salt from a pit on a Bronze Age settlement in north-western Hungary at Lébény (Németh 2011; Németh 2013). This latter is rock salt and presumably came from the Alpine sources; the Cretan pieces are sea salt, and thus not our concern here. A record from the 1930s of a find near Kraków in Poland cannot be regarded with any certainty but it may well have been rock salt (Reyman 1934).

2The other thing about salt concerns its usage. We tend to think of salt as being something that is used primarily for human consumption, to give our food more savour (i.e. taste), or in peasant societies for preserving foodstuffs. Today, human consumption accounts for only a tiny amount of the salt produced in mines, rather more from lagoons and pans; the great majority of mined salt is used on roads in winter, and in a range of industrial processes. And of course when you look at the salt spread on roads, you definitely would not want to eat it. First it is in coarse grains, much too coarse to try to add to your food; second it is far from pure; it contains a sizeable component of impurities, and of other material from the parent rock. The colour is not important, as that can vary, but one can often see lumps of rock salt in areas with salt massifs that do not contain much salt. Much rock salt is full of impurities, and that is an important factor when we come to think about the prehistoric production of rock salt. In other words, you cannot just extract lumps of halite (the commonest rock salt mineral), grind it up, and eat it; it needs to be particularly pure, and ground to a size suitable for manageable consumption.

3You can buy a packet of rock salt today in the supermarket, but it will have come from very pure sources, and have been ground to a size where the lumps or nodules will fit into your salt mill. Interestingly, our shops today often sell “Himalayan sea salt”, which seems something of a puzzle given that the Himalayas are rocky mountains and not exactly next to the sea; this is in fact rock salt, but like all salt of this kind derived from ancient oceans, so that no trade descriptions legislation is being broken.

4We can see salt mining taking place at the present day in many places across the world. The countries of the Caucasian area are no exception; a large piece of rock salt from Armenia sits in the Georgian National Museum and was collected by the Austrian geologist and archaeologist Friedrich Bayern in 1859.1 The conference heard about the work at Duzdaği in Azerbaijan led by Catherine Marro (Marro, Bakhshaliyev, Sanz 2010), while Thomas Stöllner and his Iranian colleagues have worked at the Chehrābād mine in Iran (Aali et al. 2012a, 2012b), though most of the published radiocarbon dates from the site indicate that the areas examined are not prehistoric but date between ca 450 BC and 600 AD. At Duzdaği, the evidence indicates a much earlier date, certainly belonging to the Kura-Araxes period, if not earlier.

5In a conference about mining, it is the extraction of rock salt, halite, that is our main concern. It is important to stress, however, that mining for salt was only one of a number of ways in which salt was produced in ancient times, then as now. Much more common in terms of production locations, at least as far as Europe is concerned, was the evaporation of salt water (sea water or brine) either through solar sources or through the application of heat; thus lagoons by the sea, salt lakes, salt marshes, or salt springs and streams were all extensively used, and they still are. The archaeological traces of this production are usually seen in the ceramic material that formed the structures in which the brine was heated, or the vessels in which it was put (briquetage). Archaeologically speaking, these are the remains that one usually finds, especially on sites of the Iron Age and, to a lesser extent, the Bronze Age. The use of lagoons and pans is much harder, if not impossible, to detect archaeologically; it is usually the circumstantial evidence of site location that is taken as suggesting an interest in nearby salty water.

6These sources and sites are not directly relevant to the subject of the conference, though as I shall show, the evaporation of brine plays an important part in the production of salt from halite, in order to obtain the crystalline salt we like to see on our tables.

7Mining for salt, or rather surface extraction (in other words quarrying) is common in peasant societies today. In parts of Muntenia and Transylvania (Romania) there are huge outcrops (fig. 1). Now, the question immediately arises: how do you exploit this salt? On a visit in 2001 to the outcrop at Lopătari near Bisoca in Muntenia, with Valery Kavruk and Doina Ciobanu, I observed a peasant busy removing lumps of rock as salt lick for his animals. At Praid lumps of rock had been collected in this way and were about to be transported home for the same reason (fig. 2). But humans need more than a lick of salt. If they are only going to use the salt for preserving food, or industrial purposes, then they need to dissolve it in fresh water and use it as a brine. The question of whether they would grind it up into fine grains that they could eat directly is a puzzling one. This is not what usually happens at the present day either in Transylvania or in Moldavia, where extensive work has been done on the ethnographic aspects of modern salt use; nor have we ever found grinding stones in our fieldwork in Romania. I return to this question below.

Fig. 1 – Rock salt massif near Bisoca, Muntenia, Romania (A. Harding).

Fig. 2 – Lumps of extracted rock salt destined for use as animal licks at Praid, Transylvania (A. Harding).

8For instance, a French-Romanian team has been studying the way salt is extracted and used in the Coza valley, Vrancea County:

In most cases, the salt blocks are destined to animal consumption, especially for ovine. Indeed, the shepherds sometimes have to regroup in order to exploit a deposit before the summering on mountain pastures (at the beginning of spring), but also in order to prepare for winter housing. The users associate with each other and the repartition depends on the amount necessary for each livestock. Considering that sheep need 2 to 3 kg of salt, the estimate amount necessary is 60 kg for a herd comprising 300 sheep during the summer season (6 months). As regards the human consumption, the salt is used after being crushed in an appropriate wooden or iron container after being diluted in freshwater (usually tepid), in order to prepare the brine (Brigand, Weller, Alexianu 2015, p. 226).

9Similar observations have been made in other localities (Alexianu et al. 2015). But let me turn to the question of mining for salt. In a prehistoric context, in Europe, one site name is indissolubly associated with salt mining: Hallstatt in the Austrian Alps. It was the first site to be investigated, and it became famous because of the Early Iron Age cemetery which lies nearby, and was extensively excavated in the 19th century. The mine itself became a tourist attraction very early as well, while mined salt was (and is still) being produced commercially. But Hallstatt was soon joined by the later Iron Age site of the Dürrnberg near Hallein, in the valley of the Salzach river and about 42 km from Hallstatt in a straight line, and the subject of extensive recent work by Thomas Stöllner (Stöllner 1999, 2002). Other salt mines in Europe are believed to have been exploited in prehistoric times, notably those at Wieliczka near Kraków in southern Poland, but it is notable that the only direct evidence for this comes in the form of pottery vessels that are supposed to have acted as briquetage. There is no indication of deep mining, and surface traces will have been obliterated; only where prehistoric sites have been excavated has it been possible to suggest salt production (Grabowska 1967; Jodłowski 1968).

10I turn now to the question of how the salt was extracted, and how it was processed after extraction. This is a far from simple matter. At the site where my colleague Valery Kavruk and I have conducted excavations in Romania, at Băile Figa near Beclean (Bistriţa-Năsăud county), the rock salt is not visible on the surface; it lies 2 to 3 m deep. It is very hard; breaking pieces off is a tough task; a bulldozer could only scratch the surface when clearing topsoil away. To give an idea of what is involved, my colleagues have filmed a man at the village of Dumitra, near Năsăud, using a modern cast iron pick and a sledgehammer weighing 15 kg. In spite of these modern tools, it still took him around 20 minutes to detach pieces of rock of any size. Similar observations have been made by the French-Romanian team working in Moldavia (Alexianu et al. 2015, p. 54). With prehistoric tools the task would obviously be much harder, if not impossible; hence the need to look for alternative methods of exploiting the rock.

11At Hallstatt and the Mitterberg, and potentially elsewhere, we know something about the tools used to break off pieces of material from the parent rock. Socketed picks (Tüllenpickel), employed notably in the Mitterberg mines for the extraction of copper ore, and end-winged picks (Lappenpickel) were used at Hallstatt. There is good evidence for these in the form of wooden hafts and in a few cases of surviving tools, for instance from Hallstatt itself (Mayer 1977, pp. 226-229, taf. 90-92) and a few other places, for instance the large hoard from Sipbachzell (Höglinger et al. 1996, pp. 41-42, taf. 20). In the Bronze Age, interestingly, this pick type is not common in the bronze repertoire of Europe, only finding analogies in some of the large hoards from Romania such as Guşteriţa and Uioara de Sus (Vulpe 1975, pp. 79-80, taf. 45-46), where one assumes a similar function applies. From the excavations at Băile Figa came a number of hafts that are very similar to those at Hallstatt (fig. 3), though it is not clear that they would have fitted into winged rather than socketed picks, because of the oval or round section of the points. We found no bronze picks in our excavations at Figa, but that is perhaps not surprising – we found no metal at all. We did, however, find a number of the waisted or grooved stone tools often called “mining tools” in English (German Rillenhämmer), always associated with mining in prehistoric contexts (fig. 4); Catherine Marro’s team has found them in abundance at Duzdaği (Hamon 2016), and they occur very frequently in or near copper mines, in many different countries.

Fig. 3 – Wooden hafts for picks excavated at Băile Figa near Beclean, Transylvania (Muzeul Naţional al Carpaţilor Răsăriteni).

Fig. 4 – Grooved stone hammers (“mining tools”) excavated at Băile Figa near Beclean, Transylvania (Muzeul Naţional al Carpaţilor Răsăriteni).

12In the Iron Age the technique was different. Whereas in the Bronze Age shafts were dug down more or less vertically into the rock, in the Iron Age adits were driven in horizontally following the salt veins; very large chambers were opened up (Kern et al. 2009). And the form of extracted rock salt pieces was different: bronze picks were used to chip around and partially under areas of the rock face in the shape of hearts; these forms were then somehow prised off the rock, presumably whole, though modern attempts to do this have not succeeded. Iron picks, of a rather different form, came in during the later Iron Age.

13At Chehrābād, to quote Thomas Stöllner and his collaborators:

The miners’ method to approach salt layers had been digging horizontal, and probably also vertical galleries into the mountain. After reaching salt deposits they extracted the salt by using tools such as picks, adzes and chisels, as is indicated by the numerous marks and impressions on walls and collapsed blocks… the general layout of the excavated parts of the mine indicates a chamber-pillar mining… It is still unclear if salt was extracted as small salt pieces or bigger rock salt lumps; if larger blocks have been exported directly or if they were grinded to salt grain nearby the mine is unknown (Aali et al. 2012b, pp. 7‑78).

14Now this raises a number of questions. First of all, outcropping rock salt like this is not usually pure enough to eat directly, as discussed above; it would need to be cleaned by dissolving in water, evaporated, and the crystals would need to be collected. Second, grinding it to a fine powder would be laborious. And perhaps most obvious, if such outcrops were useful for immediate human consumption, why would anyone go to the trouble of using any other technology, such as brine evaporation, wooden troughs, or anything else? Clearly there is more to it than just breaking off some lumps of rock and putting them on your food. I have asked the colleagues from Vienna who work at Hallstatt what they suppose happened to the rock salt the miners there extracted; their reply is as follows:

For Hallstatt we assume that in Bronze Age they produced small-piece salt and delivered it in bags. In Early Iron Age they produced big salt plates. We have no indication either for Bronze Age nor for Iron Age if and in which form salt was processed. This is a very interesting question indeed! We do not know a single grinding stone from Hallstatt (Kowarik, in litt., 16/05/2016).

15In other words, there is no information on the topic at Hallstatt, and that is in itself an interesting fact. If there are no grinding stones at Hallstatt, clearly the rock salt was not ground there; if it was ground at all it was done somewhere else, presumably at consumer sites or some intermediate processing station. In fact, the salt was probably not ground but dissolved in water and re-evaporated in order to obtain salt in pure crystalline form. Here again is what Kerstin Kowarik has to say about Hallstatt, in this case about the large pool one sees on the tourist route:

The entire chamber was artificially filled with water up to the ceiling. The water would then leach the salt out of the rock (Kowarik, in litt., 13/05/2016).

16This would produce brine, which would have to be evaporated – in this case it was allowed to run down the mountain in a pipe (Soleleitung) to a Pfannhaus (“pan house”) in Hallstatt village, where it was evaporated using a well-understood technology, also found at Bad Reichenhall and other places. Later the Hallstatt works could not cope with the volumes being supplied, so from around 1600 it was pumped to the saltworks at Bad Ischl. The point is that in medieval and early modern Hallstatt rock salt was not being ground up, and this was probably the case for prehistoric times also.

17This has important implications for the technology used in Bronze Age Romania, which I and Kavruk have been investigating over the last 15 years. We have identified a particular technology, which we call the “trough technique” after the large wooden troughs (fig. 5) that have now turned up on five sites and are implied by one more, and have been thought to represent a means of enabling rock salt to be broken up more easily, by allowing water to drip onto the rock surface, thus creating depressions that could be enlarged by wooden wedges. Quite how the troughs were used has been a matter for speculation since the first example was found, in the early 19th century (Preisig 1877). They seem to have been used in conjunction with wattle-sided pools or ponds, which may also have served for dissolving the rock salt and thereafter storing the brine. It is also possible that the troughs were used in a different way, since they seem usually to appear in groups or pairs. This makes me wonder if they might have served to concentrate the brine, being used in series rather than in parallel, as shown diagrammatically in fig. 6.

Fig. 5 – Wooden trough removed from the stream bed at Băile Figa near Beclean, Transylvania (Muzeul Naţional al Carpaţilor Răsăriteni).

Fig. 6 – Diagrammatic representation of a possible way in which multiple troughs were used in sequence (A. Harding).

18Was rock salt in prehistory ground to sizes convenient for human consumption? The question remains unclear. I have indicated above that no grinding equipment has been found at Hallstatt, nor at any of our Romanian sites. But the ethnographic accounts, including that quoted above, indicate that grinding does take place at the present day, and Aali et al. suggest it as a possibility for Chehrābād, though without having found any definitive evidence. In this connection the observations made at Duzdaği by Caroline Hamon, both at the conference and in print, are very important (Hamon 2016). There are grinding stones at that site, but not many, and there is little or no indication that they were used for grinding the rock salt; but on the other hand there are numerous hammers, waisted and other, which seem to have served the miners in the various extraction activities.

19Finally I would like to introduce a topic which has perhaps been insufficiently considered: the relationship between people and the rock. When we look at a man picking at the rock surface, we ourselves are barely able to enter into a world where that surface, that mineral, was a matter of life-giving force, something that one has to enter into, something that is an essential part of what it is to live in an environment where the rock is what gives one the ability to live one’s life in the customary way. People, and according to the Hallstatt evidence that means women as well as men, had a relationship with the rock which was extremely intimate: cutting a channel into the living rock was both a means of acquiring the white gold but also a violation; the cutting of a living and life-giving commodity. Perhaps it is not so surprising that various aspects of the mining process achieved cultic status. St Barbara is the patron saint of miners, apparently because of her association with lightning and therefore explosives; shrines to her are found in several of the salt mines of Europe. Perhaps it was something of the sort which caused a Bronze Age mining pick to be broken, its tip rammed into the wings of the pick, and the whole thing pushed into a crevice on a steep slope high above the Hallstättersee (Windholz-Konrad 2012, pp. 120­‑125, Abb. 4-5). And let us not forget that for all the superficial similarities between salt mining and metal mining, the two things are very different. Unlike copper or gold, salt is something you consume; by digging a tunnel or shaft into a body of salt you were entering the body of the thing you were going to consume; you could smell it, or taste it, as you worked inside it. A relationship with a body of salt is quite unlike that with any other mineral.

20As ancient miners contemplated a wall of rock salt, with its life-giving potential and its swirling patterns reflecting the movement and deposition of ancient water bodies, they will have known that its extraction represented an enormous challenge and a huge amount of work, but a challenge which they overcame by devising a series of ingenious devices, and work which they – all of them, male and female, young and old – put into the task. As archaeologists we are able to admire their achievements, while being thankful that the salt on our dining tables reached us with no more effort on our part than a trip to the shops.