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 lighter colored 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 apparently exhausted while the cheaper and similar purple agates coming from Mexico and Indonesia hamper any motivations to mine the Holly Blue agates.

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Rough Appearance: Irregular Geometric shapes with purplish to gray agate showing.
Agates are gray to deep purple, often with banding. (Pre-1980s agates are more bluish)