I have read many times here that silver is NOT a heavy metal, but researching 
for another reason I ran across this link that specifically lists silver as a 
"heavy metal", though it does not list silver as one of the "commonly found" 
toxic metals. So is silver a heavy metal or not? Anybody know its specific 
gravity?
  I am not about to give up my CS, but would like to be accurate when 
conversing with people who say silver is a heavy metal. I don't want to say is 
is not, if in fact it is............
paula
http://www.lef.org/protocols/prtcl-156.shtml#intro

There are 35 metals that concern us because of occupational or residential 
exposure; 23 of these are the heavy elements or "heavy metals": antimony, 
arsenic, bismuth, cadmium, cerium, chromium, cobalt, copper, gallium, gold, 
iron, lead, manganese, mercury, nickel, platinum, silver, tellurium, thallium, 
tin, uranium, vanadium, and zinc (Glanze 1996).........
Definition of a Heavy Metal
"Heavy metals" are chemical elements with a specific gravity that is at least 5 
times the specific gravity of water. The specific gravity of water is 1 at 4°C 
(39°F). Simply stated, specific gravity is a measure of density of a given 
amount of a solid substance when it is compared to an equal amount of water. 
Some well-known toxic metallic elements with a specific gravity that is 5 or 
more times that of water are arsenic, 5.7; cadmium, 8.65; iron, 7.9; lead, 
11.34; and mercury, 13.546 (Lide 1992).
Commonly Encountered Toxic Heavy MetALS
  a.. Arsenic 
  b.. Lead 
  c.. Mercury 
  d.. Cadmium 
  e.. Iron 
  f.. Aluminum