Mining was confined to the getting of gold from riverbeds, where it had been concentrated by Nature, and possibly on a small scale by amalgamation with quicksilver. Copper and tin were found and used, and indeed to-day the natives in certain places beat out large copper vessels[11] and offer for sale masses of rude copper _matte_,[11] from their primitive earthen furnaces. The obsidian mines of Itzala furnished them with tools for the cutting of stone, sculpture, and other purposes, and for their terrible weapons of war. [Footnote 11: I have used and purchased these articles in the State of Durango.] Sculpture and painting were very rudimentary, the former being confined chiefly to the representation of repugnant deities, although the carved stone edifices and temples were in some cases singularly beautiful, as elsewhere described. The sculptured figures of Mexican deities, in some cases, remind the traveller strongly of similar representations of the Incas,[12] such as exist in the fastnesses of the Andes of Peru. The famous Mexican Calendar stone, weighing about fifty tons, which was brought for many miles over broken country to the Aztec capital, is one of the most remarkable examples of their sculpture. Numerous smaller examples of prehistoric sculpture exist, some beautiful in design and execution. The feathered serpent is a frequent symbolical device upon these native works of art. [Footnote 12: The figure of the conventionalised serpent-god on the onyx tablet found in 1895 in the Valley of Mexico and taken to the Museum of Chicago (see Holmes's "Ancient Cities of Mexico") strongly reminds me of the figure on the stone from Chavin in Peru (see "The Andes and the Amazon").] [Illustration: PREHISTORIC MEXICO: RUINS OF TEMPLE AT CHICHEN-YTZA, IN YUCATAN.] Pottery was made without the potter's wheel, by modelling; and painting and burning were practised. Musical instruments were also made of clay. Trade was conducted in ancient Mexico in great fairs or marketplaces, not in shops, and indeed this custom is still that preferred by the Mexican natives of the _peon_ class to-day. The currency consisted of quills of gold-dust, small pieces of tin, and stamped copper, and barter was a principal mode of transaction. The merchants were an important class, carrying on extensive operations and expeditions far beyond the borders of the empire, under armed escorts, and they occupied often a position of political, and even diplomatic nature, such as was a peculiar feature of Aztec civilisation.