The only fiction book entitled 'Silver' listed in the British Library Catalogue is by Graham Masterton (pub 1986 in hardback, 1987 in paperback).
The book's synopsis (taken from the official Graham Masterton website) is as follows:
"Masterton's main character, Henry T. Roberts is similar to Collis Edmonds in Railroad. Women had always loved Roberts, but only one of them was determined enough to follow him across the American continent. As Roberts chases his fortune he becomes aware of the temptations and guilt that threaten to destroy him. He is faced with a tough decision: being disloyal to a dedicated woman, or becoming many times richer than he deserves. A well written book which beautifully captures the magic of a different era. "
I'm not sure if this is the title you're looking for. If it is, it's available, in paperback, from Amazon.
Chris