How old is stone

["Nally, Thomas" <TNally@xxxxxxxx>]

Some info from the net:

Soapstone and Talc

General Information
Soapstone deposits in Arkansas were first discovered in 1888. The =
massive soapstone typically consists of 50 to 80 percent talc =
(Mg3Si4O10(OH)2) admixed with chlorite, serpentine, pyrite, quartz, =
calcite, magnesite, and dolomite. The rock is either massive or flaky =
depending on the talc and chlorite content. It is soft and has a =
slightly greasy or dry soapy feel when rubbed on the hands. Soapstone =
and talc are usually associated and are generally grouped together.

Mining
One company operated soapstone mines at various open pits along a narrow =
4-mile-long belt in northeastern Saline County and processed the rock at =
a grinding plant at Bryant, Saline County. The soapstone was crushed, =
dried, ground to a fine powder, passed through a cyclone separator, and =
bagged. The material was used principally as an inert filler in paints, =
rubber, and roofing products, resurfacing for tennis courts, coatings =
for pipes, in brake shoes, and as a carrier for insecticides. Although =
talc is an extremely versatile mineral, Arkansas soapstone had only =
limited application as fillers in ceramic ware, tailor's chalk, pencils =
for marking steel, heat and electrical insulators, and slabs for the =
construction of acid-resistant tanks and for table tops and ornamental =
carvings. Most Arkansas production was used as inert fillers and in =
brake shoes.   Mine output averaged about 1,500 short tons of soapstone =
annually.  The single company permanently closed their mine and plant =
operations in 1999.

Geology and Resources
The soapstone-serpentine deposits are probably Precambrian in age and =
exist as exotic lenses or masses in shale and chert beds of Ordovician =
age. They were most likely injected into the younger rocks by tectonic =
processes. Because the serpentine pinches and swells in breadth and =
winds sinuously, lenses of soapstone appear as isolated bodies, though =
in places they may join at depth. Evidence suggests that the 5 mined =
deposits contained  more than 500,000 tons of soapstone in total. 

Cox, T. L., 1988, Tectonically emplaced serpentinites of the Benton =
uplift, Saline County, Arkansas, in Colton, G. W., ed., Proceedings of =
the 22nd Forum on the Geology of Industrial Minerals: Arkansas =
Geological Commission Miscellaneous Publication 21, p. 49-61.
Sterling, P. J., and Stone, C. G., 1961, Nickel occurrences in soapstone =
deposits, Saline County, Arkansas: Economic Geology, v. 56, p. 100-110.
Stone, C. G., and Sterling, P. J., 1964, Relationship of igneous =
activity to mineral deposits in Arkansas: Arkansas Geological Commission =
Miscellaneous Publication 8, 23 p.
Wicklein, P. C., 1957, Geology of the nickeliferous soapstone deposits =
of Saline County, Arkansas: Columbia, University of Missouri, M. S. =
thesis, 68 p.