text: While all the metals of antiquity but tin and lead occur natively, only gold and silver are commonly found as the native metal.
  * Gold and silver occur frequently in their native form
  * Mercury compounds are reduced to elemental mercury simply by low-temperature heating (500 °C).
  * Tin and iron occur as oxides and can be reduced with carbon monoxide (produced by, for example, burning charcoal) at 900 °C.
  * Copper and lead compounds can be roasted to produce the oxides, which are then reduced with carbon monoxide at 900 °C.
  * Meteoric iron is often found as the native metal and it was the earliest source for iron objects known to humanity