S5002316

186 MSeckó 2chrovico in Bohemia

if not as many as 6*6 (Biolonin 1992,186). This menns that (for a group of throo) 66 days wouid have boen spont by this production activity at MSeckó Żohrovicc.

It is impossible to calculato, from the estinmtions above, tho numbor of iron making campaigns in MSeckó ŻehroWce (actirities within ono campaign aro supposed to cover a greator part of a year). The question is whether it wouid be possible to ascribe one bloomery micro-site to one campaign: the two assumcd bloomery micro-sites in MSeckó 2ehrovice wouid conseąuently represent two iron-making campaigns.

Both agricultural and iron making activities could possibly have been managed by a relatively smali group of people on the site (similarly, Crew 1989; Jflns 1994). Assuming the average number of in-habitants of one settlement as 16 persons, then the number of persons in the productive age wouid have been 8 (4 families of 4 persons, one half of which were of working age, cf. Neustupny 1983; Neustupny - Dvorak 1983). Of this number less than half could have been involved in the activities connccted with iron making, which did not neces-sarily coincide with the season when the agricultural work took place (cf. estimates of the division of work throughout the year Cleere - Crossley 1985, 50-51; Magnusson 1993,485; Voss 1994). It should be kept in mind that we are now dealing with the whole production of iron presumed in the investigated part of the site, which most probably was not achieved in one campaign alone. Spread-ing production over morę years (morę campaigns), i.e. less volume of production in one year wouid burden the local comm unity much less.

Iron ore

With regard to iron making on the site an effort was madę throughout the investigations to iden-tify the rocks and materiale that could have been used as iron ore. The ochre-coloured to red or even purple ironstone (ferric/ferruginous sandstone or Ortstein), the fragments of which were found in the ploughsoił and in the layers and lills under-neath, was taken for iron ore during the invcs-tigations, as it was the only materiał containing iron that was found. According to the analyses carried out (Pleiner this volume; Kuivartovś this volume; Malkovsky forthcoming), though, the iron eon tent in ironstone (up to 10% of Fe) is too Iow to be used as iron ore for iron production. The finds nevertheless proved in several cases that it was processed at the Bite, although perhaps only tentatively. Other materials which could serve as sources of iron will also be discussed in this sec-tion.

The accumulation of fragments of ironstone at several manufacturing sites that have already been described, i.e. in feature 1/79 (the bloomery workBhop; tho ironBtono sample from the feature could have boen, according to tho minoralogical analysis, oxposed to hoat), 1/86 (containing iron-stono and cindors), 27/85 (containing ironBtono with traccs of flring at tho temperaturo of 300-350°C, marlstonos and charcoal), and 48/86 (with ironstone, quartz pebblos, marlBtono and tracos of flring), is romarkablo. Tho ironstone was (or could be) expo8ed to firo in these featuros and probably roasted along with various additives, which might represent experiments aimed at ore upgrading before its charging in the furnace.

In other features the ironstone occurred together with further iron making debris and it might possibly have been placed there even sccondarily (sites 5/80 and 11/86).

The total weight of the ironstone obtained during the investigations was c. 133 kg, the heaviest accumulation being that from features 27/85 (56 kg) and 11/86 (30 kg). The density of this ironstone (Fig. 104-105)) also indicates sites of iron manufac-ture on the site. In generał, it can be claimed that tho finds of ironstone accompany manufacturing sites where the "ore" was processed, as well as the iron smelting features. They occur at other places on the settlement as well, where their occurrence may be natural, but it may also be related to the exploitation of ferruginous layers in the local Cenomanian sandstones. The ore Processing features indicate that this activity took place on the site.

The Iow iron content has been already mentioned which wouid prevent the ironstone recorded during the investigations, from being a suitable iron source for metallurgical production. The ironstone found wouid then possibly represent only negative selection after screening the richer pieces. It remains, however, ąuestionable whether these richer pieces were available in sufficient amounts to represent the main source of raw materiał for local iron production.

The use of ironstone is also indicated by finds obtained by surface prospecting in the Lodóni-ce region, which can be presented here only in a preliminary form (cf. Venclovó et al. fortheom-' ing): localities with iron-smelting components, or rather with finds of bloomery slag, accompanied almost olways by the sapropelitc industry, occur in most cases not in the vicinity of the sapropelite outerops (and the accompanying ferruginous materials, sce below), but near the occurrences of Cenomanian sandBtone which contoins the above mentioned ferruginous layers and accumulations of ferruginous concretions. This iB also the case of the MSeckó Zehrovice site, which is situated directly on tho Cenomanian sandstone and, at tho same time, at a distance of 5.3 km from the nearest sapropelite outerop.

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Industrial settlement, LT B2-C1    187

Tho only raw materiał richer in iron, discovered on tho sito, is a fragment of a grey-black, in places rusty-brown rock found in tho ploughsoil base in scctor 10 of trench 29. According to the analyses (Plcincr this volume, s amplo 8/92; Kutvartovś this volumc, sampie 8), it is a ferruginous (goethito) fcrrolito, a foHsil-weathering product, containing over 45% of ferric compounds. It could have been collectod on the surface along with other ferruginous sandstones and concretions.

Another source of iron worth considering in the region under study is the pelosiderite occurring within the Kounov Group of Seams, which could have been obtained during the mining of sapropelite (Kużvartovś this volume; Pleiner this volume; Pleiner - Princ 1984, 171 with ref.). Iron is also present in the chemically precipitoted ferruginous layers adhering to the blocks of raw sapropelite, found sometimes at La Tinę settle-ments in the region (Venclovś et al. forthcoming). The fact that the evidence of iron production and sapropelite working were found repeatedly in as-sociation in the same settlements, suggests the use of this ferruginous materiał.

According to M. Malkovsk# (forthcoming), pelosiderite is found in the form of lenticular and globular concretions not only within the Kounov Seam itself, but the concretions were dragged out by solifluction from the valleys, cut by eroeion, also into other places. Their occurrence also coin-cides with the prehistorie metallurgical localities in the region. The pelosiderites are very rich in iron, they could easily have been obtained from shallow depths of up to 2 m and they occur in large amounts (until World War II they were used in the Kladno region as iron ore along with the Nućice ore) and they are considered by M. Malkovsky as the only possible source for iron production in the La Tinę period. The fact that they were not recorded during the investigations at Mśeckć 2ehrovice rather pointa in favour of this theory (all the suitable materiał had been used up?). An Occidental surface find of a typical pelosiderite concretion found directly on the sito was however shown to the present author in 1994 by a local forestry worker.

Fuel

Charcoal was used as fuel in the features senring for iron production in the La Tinę period. Neither charcoal heaps nor features used for its storage have been found on the site, and the only source of information about the fuel used, are the charred wood fragments. Only the carbanized wood from roaBting pit 27/85 could be identified (Oprani this volume) as coming mainly from the oak (30 fragments), rarely from pine (3 fragments). The finds of charred wood from the other manufacturing sito* were very sporadic and were preserved only as tiny fragments that could not be treated by the analyses.

The wood from sunken hut 3/86 which was inter-preted as a sapropelite workahop most probably belongs to timber, and the wood from the hearth to ordinary firewood (the processing of sapropelite did not involve any technologies using heat). The wood from this feature was, similarly as in production feature 27/85, mainly oak, while pine and other types of wood were less freąuent.

According to the analysis by E. Oprani (this volume, Table 1) the same ratio of tree species is represented in the find collection of wood throughout the settlement: oak, the most comraon find, is followed, in greatly reduced numbers, by pine, then hornbeam (two cases only), mapie, birch, hazel etc. E. Opravil considers subierophile oak groves to be the main plant community in the surrounding countryside and it may be pre-sumed that it was oak, dominant in the finds, that was used for making the charcoal necessary for bloomery production.

Ihe observation by E. Oprani conceming the large development of undergrowth in the local woodland is remarkable in relation to fuel for local iron smelting. It is morę suitable to use wood of a smali diameter for the production of charcoal, i.e. branches or bush (Bielenin 1992, 324) or even cultivated thickets (coppicing, cf. Voss 1993). Al-though there is no evidence for this type of forest cultivation in the prehistorie period, it should be taken into account when considering the estimates of fuel consumption in the bloomeries. Coppicing might have considerably reduced the consumption of wood per hectare (Mighall • Cham bers 1993, 73). Sparsely forested woodland with abundant undergrowth may reflect both extensive felling of trees in generał and the selection of young growth for the production of charcoal.

The estimates of the wood consumption per volume of iron produced wouid be very ap-proximate as we know neither the technical parameters of the local furaaces nor the quality of wood from the local forest. We use as a starting point estimates valid for furnaces from other regions and for modern forestry. The calculation is based on the assumed weight of the raw bloom calculated from the weight of the bloomery slag gained during the investigations on the site. The estimate of the weight of the raw bloom (i.e. the average of the min. and max. estimate) is 132 kg, which represents the lowest possible ąuantity produced on the site. The amount of raw bloom actually produced is not known and for the follow-ing estimates a ąuantity frve times higher (660 kg) will be used. Even this number can be considered underestimated when the area inves-