thanks! we have a 100 year old lake (Medina Lake, Medina County, Texas) that's been drying up and I've been finding bottles and such from 1907 on. most of the glass found has little to no iridescence because they have been submerged under water for decades. I can see very faint letters on one of the ribs, but all I can make out is cococ (possibly). the muck on it was hard to take off, about as hard as the bottles I find from the teens up to the twenties.