General/Base Info:
Portland Mill [Colorado Spring]
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Info Last updated: 23.05.2021 (08:50:52)
This is the large Portland Mill along the Short Line in Colorado Springs, built in 1902. It was a chlorination first, later also a cyanide mill built for the exclusive treatment of Cripple Creek ores. It converted the crude gold-bearing rock into bullion. The Mill closed in 1918, and as with the grade of the Short Line in this area, near impossible to find any traces of it judging from aerial photos I've seen.One of the Big Mills. Portland Mill at Colorado Springs
Photo by: Unknown
My Collection; From page 38 in the 1908 Official Summary of the Certified Reports of Companies Listed on the Colorado Mining Stock Exchange; from a 300dpi scan.
Media ID: 366
Id No. (Mine / 1902 map):
Date Located / Formed:
Colorado Springs
Location Map Description:
Discovery / Formed by:
  • Portland Gold Mining Company ()
Dismantled / Removed
Fate details:
One source I read say one date, two pages later it say another date that this mill closed down, rather confusing. Probably the last ore was treated by March 3, 1918 and the Mill it self closed totally down by April 1, 1918.
graphic for visual presentation of text The Colorado Springs mill of the Portland company commenced work in June 1902, and has extracted gold worth over $35,000,000 from Portland and custom ores.
graphic for visual presentation of text That the Portland company would close its Colorado Springs mill was intimated in the report for 1917. High-grade ore will now be treated at the Independence mill at Cripple Creek. Some machinery will be transferred, meanwhile this ore goes to the Golden Cycle plant at Colorado City.
Owned by:
  • Portland Gold Mining Company
Known claims:
    Location Claim Description:
    Patented Date:
    Mineral Certificate No.:
    General Land Office No.:
    Known Transportation Connection:
      Extra Info/Details [Linked at One Time to the Entity]:
      Chlorination Mill & Cyanidation Mill
      Known Producing Info:
      March 1918 treated 8,370 tons, at a value of $17.50 per ton.
      General notes:
      Built as a chlorination plant in 1902 and changed to cyanidation in 1912 and closed March 31, 1918 as per Annual Report for 1918 {M&SP March 15, 1919, p.374].