I have never heard of silver madrone either Tom. Pacific madrone is the
only variety that I know of and that is what grows in your area. As with
many tree species and firewood there are often different common names
that people use for the same trees. Some people I know in that area call
madrone laurel and for all I know maybe some call it silver madrone
too, but it all comes from the same kind of trees. I did a google search
for "silver madrone" and the only thing relevant that came up for that
term was some ads from some guy in Southern Oregon trying to sell silver
madrone.
The only guess I have is maybe he
is referring to wood that comes from standing dead madrone trees. When
they die and are left standing a while the bark falls off and they turn a
color that he may be calling silver. I would call it gray but it can be
kind of a glossy gray so maybe that's it. It's just a guess. Silver
madrone does sound like a better marketing term to use than glossy gray
madrone.
Have you called him and asked him? If you do come back
and let us know what you find out. Or have him come to the forum and
tell us all about it himself. He can even give a shameless plug for his
firewood business here and maybe sell more of his silver madrone.