text: Nine chemical elements – carbon, sulfur, iron, copper, silver, tin, gold, mercury, and lead, have been known since before antiquity, as they are found in their native form and are relatively simple to mine with primitive tools. Around 330 BCE, the Greek philosopher Aristotle proposed that everything is made up of a mixture of one or more roots, an idea originally suggested by the Sicilian philosopher Empedocles. The four roots, which the Athenian philosopher Plato called elements, were earth, water, air and fire. Similar ideas about these four elements existed in other ancient traditions, such as Indian philosophy.
  A few extra elements were known in the age of alchemy: zinc, arsenic, antimony, and bismuth. Platinum was also known to pre-Columbian South Americans, but knowledge of it did not reach Europe until the 16th century.