Nuclear labs are where you might come across platinum - it can be formed I to crucibles to heat test samples beyond 1000 deg C with contaminating them. Which is why scientific grade platinum is purer than jewelry grade (both are beyond 99 percent).
At a nuclear labs near me there was a bit of a panic when some platinum mesh couldn't be found. Informal investigations by the scientists led them to a recently retired old boy who had taken them with him because he thought it'd make a good trellis for his roses. The equivilent of the labs annual operating budget supporting Bob's roses! After they explained this to him, he was apologetic and the platinum recovered, without involving anyone else.