Vermiculite

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Vermiculite is a mica-like silicate mineral of the general formula (Mg,Fe2+,Al)3(Si,Al)4O10 (OH)2 . 4H2O that rapidly expands upon heating, resulting in a low-density material. The expanded material is used as a lightweight aggregate and insulation in the construction industry, a carrier for fertilizers and a soil conditioner in agriculture, a fragrance carrier, and a filler and texturizer for plastics and rubber.

Vermiculite was observed during mining of iron ore in the 1940’s and 1950’s at Magnet Cove, Hot Spring County. Residual flake vermiculite originated from the iron-rich mineral biotite in igneous rock, then processes of alteration and weathering created vermiculite. These deposits have unknown commercial potential. Exploration for vermiculite deposits is straightforward since they are the products of surface and near-surface weathering processes.

Although Arkansas does not have any vermiculite mining operations, companies in Arkansas expand imported vermiculite, placing Arkansas among the principal expanded-vermiculite producing states in the United States.

References

Erickson, R. L., and Blade, L.V., 1963, Geochemistry and petrology of the alkalic igneous complex at Magnet Cove, Arkansas: U. S. Geological Survey Professional Paper 425, 99 p.

Williams, J. F., 1891, The igneous rocks of Arkansas: Arkansas Geological Survey Annual Report for 1890, v. II, 457 p.

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