What do the terms in the title have in common ? All three refer to vermiculite, a grayish, basaltic mineral. Jefferisite is a synonym for vermiculite, named after the American mineral collector, William Jefferis (1820-1906). Vermiculite derives its name from the Latin “vermiculare” which means “to breed worms.” This description alludes to the exfoliation (or expansion) of the mineral when exposed to intense heat. And finally, all of this ties in to Albemarle County with the old Charlottesville Quarry, located in Shadwell. In fact, Virginia is one of the larger producers of vermiculite (although today, the closest mining of this substance is in Louisa County). The mineral is extracted from deposits that are between 1.5 and 3 billion years old. It was discovered by geologists in 1824 and is still used in insulation, fireproofing, packing material, and even as a substrate for the incubation of chamelon eggs.
To date, 86 known minerals have been located within Albemarle County. Accordingly, old county maps show dozens of mines and quarries that were dug for copper, gold, sulpher, soapstone, slate, limestone, etc. Perhaps the most remarkable thing about this mineral is that its synonym “Jefferisite” is one of the only Albemarle County names beginning with “Jeffer…” that does not refer to the former president.