Skip to main content
Scientific American
  • Sign In
  • |Newsletters
  • COVID
  • Health
  • Mind & Brain
  • Environment
  • Technology
  • Space & Physics
  • Video
  • Podcasts
  • Opinion
  • Subscribe
  • Current Issue
  • Sign In
  • Newsletters
      • Share
      • Latest

      Memorial Day Flash Sale!

      The Sciences

      Classification of Igneous Rocks

      • By H. Warth on May 24, 1913
      • Share on Facebook
      • Share on Twitter
      • Share on Reddit
      • Share on LinkedIn
      • Share via Email
      • Print
      Advertisement

      ABOUT THE AUTHOR(S)

        Advertisement

        Newsletter

        Get smart. Sign up for our email newsletter.

        Sign Up

        Support Science Journalism

        Discover world-changing science. Explore our digital archive back to 1845, including articles by more than 150 Nobel Prize winners.

        Subscribe Now!Support Science Journalism

        Follow us

        • instagram
        • soundcloud
        • youtube
        • twitter
        • facebook
        • rss

        Scientific american arabic

        العربية
        • Return & Refund Policy
        • About
        • Press Room
        • FAQs
        • Contact Us
        • Site Map
        • Advertise
        • SA Custom Media
        • Terms of Use
        • Privacy Policy
        • Your US State Privacy Rights
        • Your Privacy Choices/Manage Cookies
        • International Editions
        Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www.springernature.com/us). Scientific American maintains a strict policy of editorial independence in reporting developments in science to our readers.

        © 2023 Scientific American, a Division of Springer Nature America, Inc.

        All Rights Reserved.

        Scroll To Top

        Support science journalism.

        Scientific American paper issue and on tablet

        Thanks for reading Scientific American. Knowledge awaits.

        Already a subscriber? Sign in.

        Thanks for reading Scientific American. Create your free account or Sign in to continue.

        Create Account

        See Subscription Options

        Continue reading with a Scientific American subscription.

        You may cancel at any time.

        Sign in.