lode

{{Short description|Part of a rock body that holds ore}}

{{Other uses}}

File:Goldveins1.jpg veins, Blue Ribbon Mine, Alaska]]

In geology, a lode is a deposit of metalliferous ore that fills or is embedded in a fracture (or crack) in a rock formation or a vein of ore that is deposited or embedded between layers of rock.{{cite book |last=Thompson|first=Joseph Wesley |year=1913 |chapter=Lode Locations |title=Abstracts of Current Decisions on Mines and Mining, March to December, 1914 |series=Bulletin 79, Law Serial 2 |publisher=Bureau of Mines, U.S. Department of the Interior |page=[https://books.google.com/books?id=4RZLAAAAYAAJ&pg=PA13 13] |oclc=29112728}} The current meaning (ore vein) dates from the 17th century, being an expansion of an earlier sense of a "channel, watercourse" in Late Middle English, which in turn is from the 11th-century meaning of lode as a "course, way".{{OED|lode}}

The generally accepted hydrothermal model of lode deposition posits that metals dissolved in hydrothermal solutions (hot spring fluids) deposit the gold or other metallic minerals inside the fissures in the pre-existing rocks.{{Cite journal|author=Fournier, R.O.|year=1999|title=Hydrothermal processes related to movement of fluid from plastic into brittle rock in the magmatic environment|journal=Economic Geology and the Society of Economic Geologists|volume=18|pages=486–497}} Lode deposits are distinguished primarily from placer deposits, where the ore has been eroded out from its original depositional environment and redeposited by sedimentation.{{Cite web|author=McGregor, Tisha|year=2000|title=Mining the Motherlode: Lode vs. Placer Mining|publisher=Wells Historical Society|location=Wells, California|url=http://wells.entirety.ca/lode.htm|archive-url=https://web.archive.org/web/20020529192125/http://wells.entirety.ca/lode.htm|archive-date=29 May 2002|url-status=live|display-authors=etal}} A third process for ore deposition is as an evaporite.

A stringer lode is one in which the rock is so permeated by small veinlets that rather than mining the veins, the entire mass of ore and the enveined country rock is mined. It is so named because of the irregular branching of the veins into many anastomosis stringers, so that the ore is not separable from the country rock.{{Cite book|editor=Wood, George McLane|year=1916|title=Suggestions to authors of papers submitted for publication by the United States Geological Survey with directions to typewriter operators|publisher=United States Geological Survey|location=Washington, DC|page=[https://archive.org/details/suggestionstoau00survgoog/page/n36 35]|oclc=7678360}}

One of the largest silver lodes was the Comstock Lode in Nevada,{{Cite book|author=Smith, Grant Horace|year=1943|title=The History Of The Comstock Lode|publisher=Nevada State Bureau of Mines and the Mackay School of Mines|location=Reno, Nevada|oclc=3145590|url=https://books.google.com/books?id=qHMPAAAAIAAJ}} although it is overshadowed by the more recently discovered Cannington Lode in Queensland, Australia.{{Cite web|author=Staff|year=2007|title=Cannington Silver and Lead Mine, Queensland, Australia|publisher=Mining-technology.com of Net Resources International|url=http://www.mining-technology.com/projects/cannington/|archive-url=https://web.archive.org/web/20071231025955/http://www.mining-technology.com/projects/cannington/|archive-date=31 December 2007|url-status=live}}{{Cite journal|author1=Walters, Stephen|author2=Bailey, Andrew|year=1998|title=Geology and mineralization of the Cannington Ag-Pb-Zn deposit; an example of Broken Hill-type mineralization in the eastern succession, Mount Isa Inlier, Australia|journal=Economic Geology|volume=93|number=8|pages=1307–1329|doi=10.2113/gsecongeo.93.8.1307|bibcode=1998EcGeo..93.1307W }} The largest gold lode in the United States was the Homestake Lode.{{cite news |last=Yarrow |first=Andrew L. |title=Beneath South Dakota's Black Hills |url=https://www.nytimes.com/1987/08/09/travel/beneath-south-dakota-s-black-hills.html |newspaper=The New York Times |date=9 August 1987 |access-date=2008-01-11 |quote=Homestake, which is the largest, deepest and most productive gold mine in North America, has yielded more than $1 billion in gold over the years.}} The Broken Hill Lode in South Australia is the largest lead-zinc lode ever discovered.{{Cite web|author=Staff|date=February 2007|title=Curnamona Geology|publisher=Department for Manufacturing, Innovation, Trade, Resources and Energy, Government of South Australia|url=http://www.pir.sa.gov.au/minerals/geological_survey_of_sa/geology/geological_provinces/curnamona/curnamona_geology}}