Literally, "seafoam" .A very finegrained calcium carbonate mineral, used to make pipes. Typically curved lilke a miniature saxophone, the step usually amber. I tried one, but could not enjoy it. I would never have smoked, except Army gave smokers a break every fifteen minutes, non-smokers got no break. All the cigarette companies gave new inductees cartons of cigarettes. Too hook them, of course.

Edit: search says "hydrated silicate of magnesium."

URL for a picture:
http://www.anatolianmagic.com/Prolist.asp?cat=50