Few works of art have been found in the neighborhood of any of the ruins.[431] Some of them, consisting of earthen or marble vases, fragments of statues, and the like, are fantastic, and even hideous; others show much grace and beauty of design, and are apparently well executed.[432] It may seem extraordinary that no iron in the buildings themselves, nor iron tools, should have been discovered, considering that the materials used are chiefly granite, very hard, and carefully hewn and polished. Red copper chisels and axes have been picked up in the midst of large blocks of granite imperfectly cut, with fragments of pillars and architraves, in the quarries near Mitla.[433] Tools of a similar kind have been discovered, also, in the quarries near Thebes; and the difficulty, nay, impossibility, of cutting such masses from the living rock with any tools which we possess, except iron, has confirmed an ingenious writer in the supposition that this metal must have been employed by the Egyptians, but that its tendency to decomposition, especially in a nitrous soil, has prevented any specimens of it from being preserved.[434] Yet iron has been found, after the lapse of some thousands of years, in the remains of antiquity; and it is certain that the Mexicans, down to the time of the Conquest, used only copper instruments, with an alloy of tin, and a silicious powder, to cut the hardest stones, some of them of enormous dimensions.[435] This fact, with the additional circumstance that only similar tools have been found in Central America, strengthens the conclusion that iron was neither known there nor in ancient Egypt.