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Iron

Lumps of iron pyrite, magnetite, and other materials were mostly shaped into mirrors, pendants, medallions, and headdress ornaments for decorative and ceremonial effect. However, concave iron ore mirrors were apparently used for firing and optical purposes by the Olmec (1500–400 BCE) and Chavin (900–300 BCE) cultures, and ilmenite "beads" may have served as hammers for fine work. The Olmec and Izapa (300 BCE – 100 CE) also seem to have used iron magnetism to align and position monuments. They may have developed a zeroth-order compass using a magnetite bar.