Sure, you could luxuriate in a spa to soak up the healing powers of 4,000-year-old thermal spring water… but wouldn’t you rather scramble around like a prospector in red clay dirt with a pickaxe? For 25 bucks, you can spend an afternoon mining for quartz crystals at Avant Mining. For $1,000, the crew will escort you to a private dig location where the earth is so lousy with crystals that you hardly need tools, and the retail value of your crystal haul is sure to be more than what you…