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Happy Mother's Day from EarthWords!

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image shows gold-bearing veins of quartz
Gold-bearing quartz veins from the Blue Ribbon Mine, Alaska. Credit: AlaskaMining at English Wikipedia, CC BY 2.5,

The EarthWord: The Mother Lode


  • The Mother Lode is a principal vein of a valuable mineral commodity, particularly gold or silver.


Use/Significance in the Earth Science Community:

  • It's also the name given to a region of the western Sierra Nevada in California. Its extensive gold deposits, and their accessibility, led to the Gold Rush of 1849.


  • In a survey of the region's mining activity in 1929 by USGS scientist Adolph Knopf, he noted that the name was misattributed. Folks mistakenly believed "that a quartz vein extends continuously from one end of the belt to the other—the Mother Lode." The vein isn't actually continuous, but the name stuck.
  • According to Knopf, the total output of the Mother Lode in 1924 was $240 million. (That's over $3.3 billion today, adjusted for inflation)

Next EarthWord: This EarthWord is your best friend in Scrabble or Words With Friends.

Hungry for some science, but you don’t have time for a full-course research plate? Then check out USGS Science Snippets, our snack-sized science series that focuses on the fun, weird, and fascinating stories of USGS science.

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