#MiningHumanStories Norte Grande, Chile, east of Iquique. The most arid climate on Earth has created favorable conditions for the developments of saltpeter deposits (caliche) since the Pliocene (about 5 million years ago). Saltpeter was extracted to process iodine and sodium nitrate (NaNO3) from early 19th century, until the 60's. Sodium nitrate was exported across the world to be used as a fertilizer and for the manufacturing of explosives. For decades, European countries we