At the close of the last century, Father Antony Sepp found out a method of extracting a small quantity of iron from stones named _ytacurù_, by dint of a very hot fire kept up for twenty-four hours. But he had scarcely any imitators, for the quantity of iron obtained was so inconsiderable, in proportion to the labour and firewood spent upon it, that it was not thought worth the trouble. These stones, which are composed of a number of very small pebbles, are of a dusky colour, mottled with black spots. In our times, somewhat more iron has been brought in the Spanish ships, but even now it is sold at a price incredible to Europeans. All the Guarany youths, on their marriage-day, and the married people at the beginning of January, receive from the Jesuit, the priest of the town, a common knife to use at table. This donation is more expensive than Europeans may imagine, as some of the towns contain four thousand inhabitants, some six or seven. Yet, notwithstanding the dearness of iron, none of us ever thought of procuring a trifling quantity of it, with immense labour, from the stones named _ytacurù_. Out of the Cordoban mountains, they sometimes dig _talc_, a sort of softish white stone, very light, and of no firmness. It consists of slender laminæ, so that it may be divided with a knife into small plates, and is sometimes dipped in water. When slightly burnt, it assumes the softness of paper and the colour of silver, and is used to make little images and other figures to adorn poor churches. Out of the numerous leaves of which this stone is composed, you will find few entirely white and transparent, for most of them are darkened with black or yellow spots. The better ones supply the place of glass in windows and lanterns; for that article was extremely scarce and dear, in 1748, when I arrived in Paraguay. I could not see one glass window in the chief colleges of the province, nor in the towns of the Guaranies. Every one made his own window of the stone talc, (which is difficult to procure,) of paper, or linen cloth; and as these substitutes were torn away by every shower or boisterous wind, was continually under the necessity of making repairs. But in the last years of my residence in Paraguay, a quantity of glass was brought thither in the Spanish ships, and the price being reduced, the houses and churches shone with glass windows. In the churches, where they look towards the south, instead of a glass window, they place a hard, white, and transparent stone, which is a kind of alabaster, and is brought at a great expense from Peru, its native soil. For the south wind, which is excessively violent in South America, at the first gust breaks all the glass that opposes its fury, often levelling whole houses, breaking enormous masts of large ships, and tearing up lofty cedars by the roots. Stones fit for making lime are to be met with in almost any part of Paraguay, but they are not found in the territories of the Abipones and Guaranies.