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Mariposa Museum

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  • Location
    Mariposa California
  • Interests
    California Mining History
  1. Mariposa Museum

    Crushing And Milling

    Does anyone know about a milling process called "Ryerson" or "Eureka" that was used in the 1860's and 70's? It was a dry stamp process that was followed by introduction of "pea sized ore" to ball mills. Used in some of the top producing mines in Mariposa County at the time, but I can't find anything on the specifics of the process such as stamp drop sequence, DPM ( drop per minute), etc. Al that I do know is that the ball mills used 1 to 2 inch diameter crushing medium.
  2. Mariposa Museum

    History Of Hard Rockmining Equipment

    Have no pictures or illustrations. It was mentioned several times in the Mariposa Gazette in the 1860's. Used at the Benton Mills operation on the Merced River to mill ores from the Pine Tree and Josephine mines as well as others located on the Las Mariposas grant properties. Out of 80 stamps 32 were these Thunder Crushers. They had to build oversize foundations for the mortars, so my suspicion is they they had larger gauge stems, bosses and shoes, and thus a heaver mortar box. One other clue was that they employed the "Ryerson" process of milling up until 1868.
  3. Mariposa Museum

    History Of Hard Rockmining Equipment

    I run a Gold Rush museum and have a pretty good handle on milling machinery but I have compiled a long list of questions that I can find no information on. I'll throw this one out: There was a stamp mill called a thunder crusher that was made in or sold out of New York and used in the 1860's in California. Apparently it was a superior performer to Hendy and many other mills made on the west coast and was said to be " guaranteed to save all the gold in the rock and some that ain't" . Is anyone familiar with this model or type of stamp mill? Millman