Require Statement Problem

[Matt White]

Hello,

I am trying some things from irb and having trouble loading the
mechanize library. When I do gem list, it is in the list as:

mechanize (0.6.10, 0.6.9)
Mechanize provides automated web-browsing

But if I go to the irb prompt and do require 'mechanize', I get:

irb(main):001:0> require 'mechanize'
LoadError: no such file to load -- mechanize
from (irb):1:in `require'
from (irb):1

What have I got wrong?