Why were platinum-group metals identified much later than gold and silver?

The identification of platinum-group metals lagged behind gold and silver by thousands of years primarily due to the difficulty of isolating them.1

While gold and silver can be readily isolated in a relatively pure state using simple fire refining, the platinum-group metals require complex aqueous chemical processing for their identification and isolation. These sophisticated techniques were not available until the turn of the 19th century.1

Furthermore, the high melting points of these metals presented significant challenges for early researchers, limiting their initial applications until methods were developed to consolidate and work them into useful forms. Although platinum-containing artifacts date back to 700 BCE, their presence was likely accidental; historically, these metals were often viewed as impurities that made gold brittle and difficult to refine, rather than as distinct elements to be identified.1