Platinum Nugget
Platinum is a new resource that arrived with the 1.6 update. Platinum has a rainbow color to it which is distinguishable from other ores.
Where Found
Platinum nuggets can be found rarely underground, sometimes seeing only one block among thousands of stone before finding another. Platinum can also be obtained via the Electric Sluice, by putting Gravel into it albeit with a small chance along with Titanium nuggets.