The Bronze age might more properly be called the copper age for this is the element from which the alloy is made. Indeed the first implements from this period were made from the pure metal though it was rapidly supplanted by bronze as the functional superiority of the alloy must have been evident to those who had the opportunity to compare the working characteristics of both.
In Ireland this period starts around 5000 years ago with the introduction of copper axes from continental Europe. This is remarkably soon after the advent of copper usage in Europe showing that trade/contact between communities at this time was quite well developed. It was not long before indigenous production of copper commenced, about 500 years later. The oldest known copper mine in Northwest Europe is at Ross Island in Co Kerry. This is not to say that stone tools fell into disuse for stone and bronze were still used contemporaneously almost a thousand years after the first copper axes appear.
West Cork and south Kerry were hotbeds of copper production as the area is rich in surface ore deposits in fact this is probably the main reason why the bronze age arrived in the region so early. At Mt Gabriel extensive workings reveal the mining methods used. A fire was built against the rockface and replenished until the rock became brittle and began to fracture. Then it was pounded with stone hammers to further loosen it and the pieces dragged out to the mine entrance. There they were broken up further into small pieces. After a selection process during which the greener pieces were separated out in order to concentrate the ore it was then heated in a furnace to 1200c to yield the raw metal.
Probably the copper was directly cast into simple ingots or in the shape of flat axeheads, a common currency in those days, using stone molds. This might have made for quite a heavy pocketfull but doubtless the rate of exchange made it all worthwhile. Small triangular crucibles are quite common. The ones I've seen have the average capacity of an eggcup but larger ones may have been similarly shaped as the triangular shape was usefull, allowing the pour to be made from any side. Some even have their own lids to help keep the heat in.
The wood used to stoke the fires was still cut with stone axes for several hundred years after mining commenced. This indicates not only the efficacy of those stone axes but also the enormous value of the end product which was deemed too precious to use in the everyday extraction process, being instead reserved as a status object. This despite that bronze axes are about twice as efficient as their heavy stone cousins.
To get an idea of how valuable the stuff was, consider this. It has been estimated that to produce 44 LBS of raw copper, a ton of refined ore had to be extracted. That's the easy part. The hard part is turning the ore into copper. It takes a lot of BTU's to smelt that much ore. Two thousand five hundred tonne representing 100 Irish oak trees felled, logged, dried and converted to coke. Consuming the labour of 100 individuals for a week. No wonder the stuff was too expensive, in the early days, to cut trees with. Such axes are frequently found in hoards of several pieces comprising axeheads only, another indication that they were as good as money in the bank. Even though such hoards may also have a symbolic ritual purpose, it is surprising they are not mixed in with other valuable objects something that again points to their use as a kind of currency.
Type 1.Early copper axes were unsocketed, had cresent shaped edges, slightly curved sides and wide butts. These are found in abundance in Ireland, three times the frequency of Britain indicating the probability that smelting was more prevalent on the more isolated island.
Type 2. The later bronze versions were similar but the butt was narrower which saved on raw materials and reduced the risk of splitting the handle.The largest of these has a cutting edge of over 8 inches and may not have been used to cut timber as only the very strongest would have been able to wield it with any degree of frequency.
Type 3. Properly known as a "Palstave" this is an intermediate form between the flat and socketed types. It looked for all the world as if someone took an I beam and squashed the end flat to form the edge. But of course it also is a casting and required a bipart mold. These palstaves were generally not as wide as flat axes.
Type 4. A still later form developed in Ireland but also exported to the continent was socketed. The advantage of this was that a young ash plant or blackthorn tree could be hafted to it without putting a hole in the wood, by cutting a small piece of trunk with a sturdy branch still attached and the trunk portion trimmed to fit the socket. The resultant implement looked rather like a shillalaigh and in fact this is probably what the ubiquitous shillalaigh is decended from. Many of these axes feature loops for lashing the head to the haft but some do not, indicating that some form of glue such as pitch may have been employed as bedding. These socketed axeheads required a sophisticated tripart mould comprising a bipart outer shell with a conical core to form the socket.
A is one side of the mold with the conical core in position.
B is the conical hollow core showing what look like breather holes
C is the other side of the mold.
Of course as soon as the advantages of bronze were realized the alloying of copper and tin were almost universally adopted but bronze production is not an idle persuit. The tin had to be procured from Cornwall. The copper is melted first then the other components heated and added to the mix with vigorous stirring. Thorough mixing is necessary because the various metals have a different specific gravity and the lighter will float to the top of the mix if allowed to do so. Casting must be done without delay to avoid overheating and oxidising the more volatile elements. The cast must also be done in a single pour as a second pour will not fuse effectively with the first. Cooling must be as rapid as possible as the constituents have a tendancy to separate into a variety of alloys if the rate of cooling is too slow. Multiple molds have been found which demonstrate the industrial nature of this effort.
While on the subject of alloys the effect of localised variation in copper ore contamination can't be ignored. Indeed chemical analysis of copper axeheads can indicate with a fair degree of certainty the region of the parent deposit. For example the deposits from Ross Island are contaminated with arsenic, antimony and silver, making their product as unique as a fingerprint.
Not only axes but other implements including a tanged chisel with an axelike edge along with a socketed gouge and drawknife have been found that look like they might find uses in the modern carpenter's toolkit. Since the island was heavily wooded at that time its not surprising that many of the tools reflect a strong woodworking tradition.
So who were these people? Well legend has it that when the "Tuatha de Dannan" arrived on the island they found another people the "Firbolg" already there to greet them. Before long the two peoples found themselves squared off across the battlefield at Moytura in an epic battle that lasted three day's, the outcome of which decided the fate of the protagonists and eventual control of the island.
Both of these Bronze age races were fond of the spear both for hunting and war as demonstrated by the wide variety of socketed and unsocketed lance/spearheads they left behind them. Some of these have been classified as knives by archeologists and indeed, depending on the length of hafting, could well have been designed to serve a dual purpose. Tanged spearheads were also produced with holes for lashing to the spear shaft. These can be looked on as an earlier technology, as the socketed varieties are quite definitely an improved design and require a great degree of skill to cast. In some of these pieces the socket extends well into the blade itself and helps form its center rib.
Which of these people used what is hard to tell for sure but it was said that Na Tuatha were shocked when they first beheld the size of Na Firbolg spears so it might be reasonable to suppose that the longer and more impressive the blade the more likely it was to have been Firbolg in origin. On the otherhand it is also reasonable to suppose that the more technically superior pieces,those that are socketed, are Tuatha de Dannan in origin. In any event Na Tuatha prevailed during the battle and the island passed into their hands. Of course weaving legend and artifact together like this is something no self respecting archeologist would be caught dead doing. So it should be born in mind that this is conjectural and probably bears little relationship to reality but it makes for great story telling and a look into the mythology of early Ireland is most rewarding and time well spent.
Early Irish Hallstatt period swords were bronze with swell center grips, leaf shaped blades, and fishtail pommels. Rivetheads are often cup shaped and filled with enamel or stone.