It's definitely metallic. The luster is pretty clearly metal. And, given the average size of a man's hand, that chunk weighing nearly 2lbs means it must be fairly high density metal too.
BUT, did you determine it's actual density? And have you done any chemical tests? It should be easy to determine the density of such a solid, compact sample.
Pt's density is 21.45 g/cm3, so if your measured density is 20 g/cm3 or higher, odds are it's a platinum-group metal in the high-density range (Pt, Ir, Os). If it's lower than 20, at the very least it's not pure, but could be an alloy of Pt and Pd/Rh (densities of around 12 g/cm3), and could also have iron (one of the common native alloys found), or it could even be a native alloy of lead and silver.
So, density first, then look to its chemical characteristics. A pure Pt nugget will not react with any acid at room temps, and will only begin to dissolve in AR near boiling.
