“...The agates coming from Sweet Home, Oregon appear to be popular in the past for their cabochons that they were often sold by gram. The agates are generally gray to purple sometimes with bandings. I couldn't understand why are they called "Holly Blue", why not "Holly Purple"? Those coming from pre-1980s digs tend to be more bluish while those found later are more purplish. Both of two known agate-producing sites had been closed, possibly exhausted...”

written by Jeffrey Anderson. More informations about agates on his website dwarves earthtreasures.