forms are usually similar to those of the stone implements, and they were hafted by lashing, with wedges, to a handle, as shown in Fig. 27, a 4; p.148. "Eared" varieties however occur, though they are rare, and a peculiar T-shaped type 1s found in some quantity, extending into Oaxaca and Guatemala. Most of the last-named are so thin that it is difficult to see what useful purpose they could have served, and it is probable that they constituted a form of currency, though the suggestion has been made that they were used as knives for cutting feathers in the preparation of feather mosaic. Bells of copper are common throughout the whole of Mexico, some in a peculiar technique which look as if they were made of soldered wire, and animal forms in the same style have been found in Tarascan territory. Close examination would seem to show that these are really cast by the cire perdue process, as described below. Great difficulties however attend the casting of copper, and it is possible that such articles contain a percentage of tin. Analyses however are lacking, and it seems certain that the presence of tin must be regarded as accidental, for though deposits of tin were found in Guerrero by Cortés, yet the inhabitants had never deliberately mixed it with copper until shown how to do so by the Spaniards. Of the mining of copper, little is known, but ancient workings have been discovered at Cerro del Aguilar in Guerrero. Abundant traces of fire are to be seen, and no less than 140 stone wedges have been collected there. Probably the process consisted in heating the blocks of ore, and driving the wedges into the resultant cracks so as to split them up into more manageable fragments. The Zapotec country was famed in old times for its copper.
In the working of gold the Mexicans exhibited particular skill, and though great quantities of the wrought metal were found by the conquerors, yet a very small percentage of the enormous amount exported since the
