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Talc
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Dolomite is a sedimentary rock composed largely of calcium magnesium carbonate. This tan dolomite was formed on an ocean floor. It was then intruded by the darker 1.1 billion year old molten diabase which came up through the Earth's crust. This hot intrusion changed the dolomite into talc.
Precambrian > Proterozoic eon > Mesoproterozoic era > Stenian period
In Death Valley, talc deposits are typically associated with the region’s complex geological history, characterized by extensive faulting and fluid movement which facilitated the alteration of magnesium-rich rocks into talc. These deposits are often found in areas where hot, magnesium-rich fluids have altered dolomitic limestones or other silicate rocks.
Historically, Death Valley was an important site for talc mining, especially during the mid-20th century. The talc extracted from this area was prized for its purity and fine grain. Mining operations in the valley targeted several well-known talc-bearing formations, often exploiting large bodies of the mineral found in seams or zones of altered rock.
Although much of the large-scale commercial mining has ceased, the sites remain of interest both for geological study and for their history related to the broader mining heritage of the region.
