Crystals of analcime measuring to 1.3 cm in size on matrix. In good condition.The Washington Mine, situated in Keweenaw County, Michigan, is a historic site embedded within the famous Midcontinent Rift geological formation. Geologically, the area is defined by ancient Precambrian basaltic lava flows and interbedded sedimentary layers that host world-renowned native copper deposits. Mineralogically, the location features hydrothermal veins containing native copper, native silver, quartz, and various associated secondary minerals. Historically, the mine was part of the intense 19th-century Lake Superior copper boom, opening during the early waves of American industrial mining exploration in the Keweenaw Peninsula, though it experienced limited commercial success compared to neighboring large-scale producers.
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