Editing Herbert Hoover (section)

===Sole proprietor===
[[File:HHoover (retouched).jpg|thumb|upright|Hoover in 1917 while a mining engineer]]

After leaving Bewick, Moreing, Hoover worked as a London-based independent mining consultant and financier. Though he had risen to prominence as a geologist and mine operator, Hoover focused much of his attention on raising money, restructuring corporate organizations, and financing new ventures.{{sfn|Whyte 2017|pp=112–115}} He specialized in rejuvenating troubled mining operations, taking a share of the profits in exchange for his technical and financial expertise.{{sfn|Leuchtenburg 2009|pp=11–13}} Hoover thought of himself and his associates as "engineering doctors to sick concerns", and he earned a reputation as a "doctor of sick mines".{{sfn|Nash|1983|p=392}} He made investments on every continent and had offices in San Francisco; London; New York City; Paris; [[Saint Petersburg|Petrograd]]; and [[Mandalay]], [[Myanmar|British Burma]].<ref>Hoover, Herbert C. (1952). ''The Memoirs of Herbert Hoover Years of Adventure 1874–1920''. London: Hollis & Carter. p. 99</ref> By 1914, Hoover was a very wealthy man, with an estimated personal fortune of $4 million (equivalent to ${{Inflation|US|4|1914|r=2}}&nbsp;million in {{Inflation-year|US}}).{{sfn|Nash|1983|p=569}}

Hoover co-founded the [[Consolidated Zinc|Zinc Corporation]] to extract [[zinc]] near the Australian city of [[Broken Hill]], [[New South Wales]].{{sfn|Whyte 2017|p=115}} The Zinc Corporation developed the [[froth flotation]] process to extract zinc from lead-silver ore{{sfn|Burner|1996|pp=24–43}} and operated the world's first selective ore differential flotation plant.<ref name="Blainey">{{cite book|last1=Blainey|first1=Geoffrey|title=The Rush That Never Ended|url=https://archive.org/details/rushthatneverend0000blai|url-access=registration|date=1963|publisher=Melbourne University Press|location=Melbourne|pages=[https://archive.org/details/rushthatneverend0000blai/page/265 265–268]}}</ref> Hoover worked with the Burma Corporation, a British firm that produced silver, lead, and zinc in large quantities at the [[Namtu]] [[Bawdwin Mine]].<ref name="Hoover" />{{rp|90–96,101–102}}{{sfn|Nash|1983|p=381}} He also helped increase [[Copper extraction|copper production]] in [[Kyshtym]], [[Russian Empire|Russia]], through the use of pyritic smelting. He also agreed to manage a separate mine in the [[Altai Mountains]] that, according to Hoover, "developed probably the greatest and richest single body of ore known in the world".<ref name="Hoover">Hoover, Herbert C. (1952). ''The Memoirs of Herbert Hoover Years of Adventure 1874–1920''. London: Hollis & Carter</ref>{{rp|102–108}}<ref name="Kennan">{{cite book|last1=Kennan|first1=George|title=Siberia and the Exile System|date=1891|publisher=James R. Osgood, McIlvaine & Co.|location=London|pages=165, 286}}</ref>

In his spare time, Hoover wrote. His lectures at [[Columbia University|Columbia]] and Stanford universities were published in 1909 as ''Principles of Mining'', which became a standard textbook. The book reflects his move towards [[Progressivism in the United States|progressive]] ideals, as Hoover came to endorse [[Eight-hour day|eight-hour workdays]] and [[Trade union|organized labor]].{{sfn|Leuchtenburg 2009|pp=18–20}} Hoover became deeply interested in the [[history of science]], and he was especially drawn to the ''[[De re metallica]]'', an influential 16th century work on mining and metallurgy by [[Georgius Agricola]]. In 1912, Hoover and his wife published the first English translation of ''De re metallica''.{{sfn|Whyte 2017|pp=119–120}} Hoover also joined the board of trustees at Stanford, and led a successful campaign to appoint John Branner as the university's president.{{sfn|Whyte 2017|pp=124–125}}