It's Thor's Outdoor Thorsday!
Of the 92 naturally occurring elements found on Earth, only 7 (all metals) are found in any kind of ‘pure’ and tangible form that would have been known to ancient peoples. Gold, Silver, Iron, Copper, Mercury, Lead and Tin. These 7 metals were often associated with the 7 known heavenly bodies by ancient peoples. Sun was gold, the Moon was silver, Mars was iron, Venus was copper, Mercury was quicksilver (or mercury as we call it today), Saturn was lead, Jupiter was tin. This also corresponds to the days of the week.