http://www.ph.ucla.edu/epi/bioter/leahylettercontents.html "...The Leahy letter, which was discovered by investigators before it was opened, contained a small mound of fine white powder, giving scientists their first chance to test and examine a substantial quantity of what they believe are highly virulent anthrax spores. FBI officials said testing on the material to try to determine where it was produced will likely take weeks..."
You're right. I guess the "small mound" was felt before it was opened?
The pics at the FBI site show no (visible) powder, just the letter held in a glove box, and not anything else that might have been in the letter.