When Mr Broderick did the rubbing, he left off two words (one at each end of the ingot). That word is "NICKEL". The bar he is holding is a Nickel Babbit Ingot:
The Great Western Smelting & Refining Co. didn't produce precious metal ingots. They made Nickel Babbit Ingots for bearings. Each end should read; XXXX and NICKEL. They are currently going for around $20 for a 48 ounce (Broderick's weighed between 4-5 pounds on a bathroom scale) ingot on ebay.