The rusting hulks of machinery and the deserted ghost towns of the Humberstone and Santa Laura mining complexes are among the last vestiges of the company towns of Chiles saltpeter industry. The Pampa desert, in western Chile, is a natural source of sodium nitrate, used for fertilizer and the manufacture of explosives. The nitrate industry produced great wealth for Chile, transforming agricultural lands in north and south America, and some areas of Europe. The nitrate boom continued until 1929 when the US Great Depression paralysed the industry, which never recovered when synthetic alternatives to nitrates became available.
