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enrlched In iron oxide by the oxldation of the orlgiual copper-iron aulphlde with the weathering solution of copper salts whlch draln further down lnto the deposit. Ronetheless, the gossans still contaln evidence of copper association and nay have been first included ln mixea for smelting for this reason of copper content with eventual recognition that lt waa an linportant ingredient for other reasona. This knowledge would then lead to the uee of limonlte alone by comparison of colour and texture with the bulk of the gos6an.

Another possible way ln whlch iron oxide may first have been Incorporated when smelting oxldiaed ores lles in the similarity of cuprlte and red iron oxide. haematite, whlch was used as a flux at Tlmna. Soraetimes cuprlte li bright red, a6 in the crystalllne form (lsometrlc-cubes, octahedron, etc_; likt galena). Horę often, however, as ln the massive lumps associated with native copper, lt ls a duli red and the similarity to haematite is striklng.

The first production of iron

The addition of flux is very important, an additlon for an effect rather than for a product. It demonstrates a growing understanding of the behavlour of materials ln fire and how their behaviour might be controlled. It also indi-cates a possible origin for the production of metallic iron even before pyri-tic ores were employed. In cases where    the    gangue    content of the    iron oxide

used was Iow, so that the Chemical activity    of the    iron oxide was    not    reduced

by combination with silica, etc. and if the iron oxide was not very well mixed in with the other components, metallic iron would have occurred as smali pieces here and there, not separated to    the    hearth    but held up in    the    surface

cinder. Its characteristics, similarly    ductile to    copper when forged    under

the hammer even lf a different colour when cold, would have been noted. That such metallic iron can even be produced adventitiously in the smelting of lead is also well established. At this stage it would have been valuable -from early texts morę valuable than silver.

Also, under conditions where the activity of iron is high but not leading to some metallic iron formation, some iron reduction into the liquid copper will occur, to be rejected from the copper as it solidifies. Where the ori-ginally dlspersed smelted copper was remelted in a crucible this iron would separate as a 'rim' of distinct materiał. It is very likely, therefore, that the earliest iron was obtained by the treatment of ores discovered through association with copper. Certainly the Romans continued to minę iron ore from sites previously excavated for copper and Pilny warns of inferior irons being ' founded upon veins of brass', the main effect of copper impurlty in the iron being to introduce hot shortness or cracking under the forging hammer.

With improvement in furnaces, better draughting, bellows, etc, and higher temperatures, morę iron would be produced and eventually it could be purpose-fully madę if required, once its association with the brown iron ore was recognised. As Bachmann and Rothenberg have already póinted out in relation to operations at Tlmna, if it were required to maxlmise the amount of iron produced ln association with copper, the use of managanese oxide instead of Iron oxide as a flux would give the desired effect.

The lnclusion of haematite instead of cuprlte is a sequence by whlch tbe connection between iron ore and the white metallic product could be recognised-Yet another posslbility is that the collection of iron pyrites of yellow/whi** metallic lustre would have attracted Interest, particularly once the sulphid* minerale of copper were being used, giving the same sulphurous smell but aP infusible and different-coloured metal in smali pieces.

Whatever the explsnatlon, the incidence of occasional Iron wtifKtł (other than me teorie materiał) in tbe Bronce Aft, from the earliest period, ^wit*' theee theories of ite adventitioue formation during the production of bronce.

The incidence of iron ln the cindere of the furnace would inerease with improved furnace operation ln teras of higher temperaturę and with maintalned CO/CO2 ratioe. It would, in fact, be nececsary to malntain a suitably mildly reducing ataoaphere in order not to produce too much metallic iron ln aasocla-tion with copper. Eventually it would be deduced how to operate the furnace to maximiae or mirilmlse the extent of solid-state iron production or simply to use the iron charge to flux silica, etc as free-runnlng fayallte slags at temperatures greater than 1200‘C.

Developaent of copper-arsenie alloys

Copper-arsenic alloys oceur as a separata distinct phase of metallurgical development at the end of the Chalcolithic and the beginning of the Bronce Age in many areas, often of considerable duration, before the use of tin to make the copper-tin alloy whlch is bronce. They tben contlnued in use together with tin-bronce for sbout 500 years. Tbere are advantages over pure copper in terms of castings where the arsenie acts as a deoxidant, and up to 72 arsenie materiał can be work-hardened very substantially by cold hanmering wlthout crack!ng to strengths equivalent to tin-bronce. Tbe question chat must be asked is how dld this materiał arise? As a minerał arsenie occurs rarely in the form of the native metal and as the sulphldes reałgar (AS2S2) and orpiment (AS2S3), brlght orange and yellow in colour, whlch are associ-ated with volcanic activity. In the copper deposits arsenie is found ln each zonę, as green ar senat es (e.g. olivenite) of similar appearance to mala-chite in the oxldised zonę, and as the sulpharsenides enargite (CujAsS) and tennantite (CU3ASS) lower down.

Also in the original deposit would be the ubiquitous arsenopyrite (FeAsS) The one feature linking all these arsenie minerale is the garllc odour produced on heating in contact with alr, as in the charcoal błock test used for determinative mineralogy in the field before modern portable analytical instru ments were available. The smell is even detectable when hammering arseno-sulphide ore for breaking.

Presumably the first recognition of the new materiał came when green stones, of similar but not identical appearance to malachite, initialły col-lected as charge gave better materiał. The only difference that could be used to be surę of a different charge and thus of a different product would be the smell associated with Processing. Other materials giving tbe same smell, particularly if they gave the same flame colour for copper, would be added to charges. Thus with contlnued mining the sulpharsenides could have been used. Once the smell was recognized as the important feature, arsenopyrite could have been employed, mixed in with the copper ores or perhaps used as a separate addition to copper melts sińce it is found wldely and is particularly common in placer deposits with gold.

By this time meltlng in crucibles as opposed to simple heartb collection was well establlshed and the possibility of re-melting metallic copper with surface additlons of concentrated minerals under a charcoal cover becomes a reality, to produce individual alloys under morę closely controlled conditions of quantlties of addition. It has been shown that tin can be absorbed into copper directly from surface additlons of stannite (tin suiphide) as well as from cassiterite under charcoal, and arsenie may have been similarly added from arsenie/suiphide minerals or from a high arsenlous oxide product. A