Period 6 element
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78.
Pierre-François Chabaneau
Chabaneau was able to easily remove most of platinum's natural impurities, including gold, mercury, lead, copper, and iron, leading him to believe that he was working with pure platinum. However, the metal displayed inconsistent characteristics. At times it was malleable, yet at times it was highly brittle. Sometimes it was entirely incombustible, yet sometimes it burned readily. These inconsistencies were a result of various impurities: rhodium, palladium, osmium, iridium, and ruthenium. These elements would later come to be known as the platinum group metals, but at the time of Chabaneau's research, they had not yet been discovered.