1) Ancient Greek metalwork 2) Atlantis 3) Precious metal alloy 
Latin, meaning: copper ore / brass 
Orichalcum or aurichalcum is a metal mentioned in several ancient writings, including a story of Atlantis in the Critias dialogue, recorded by Plato. According to Critias, orichalcum was considered second only to gold in value, and was found and mined in many parts of Atlantis in ancient times. By the time of Critias, however, it was known only by...
a brass rich in zinc, prepared by the ancients.