Topazos | Not to be Confused with Topaz
Topazos was an ancient name for the gemstone known today as peridot. It's believed to have been discovered around 300 BC on St. Johns Island or Zabargad as it's known in Arabic.
In references online the names Topazos and Topazios are both used in relation to the island and the gemstone peridot. In John Bostock's translation of Pliny the Elder's works Naturalis Historia both are referred to as "topazos". Topazios is likely to have come from the Greek word for "topaz" which is "tοpáziοs".
In most cases where the word topaz has been used historically it's believed the stone is probably peridot. The mineral known today as topaz is not believed to have been known much before the 1700's.