Occoneechee Mountain -

Active Mine

Active Mine

An active mine is present on Hill Number 1 (see figure); the mine has been in operation since the 1960s. The mine is located in a large lense-shaped body of pyrophyllite and andalusite just south of Hillsborough, North Carolina. The ore body parallels the regional strike of the metavolcanic rocks. The ore body contains, pyrophyllite, quartz, andalusite, diaspore, topaz, sericite, lazulite, pyrite, rutile, and secondary phosphate minerals. Numerous cubic molds of pyrite crystals are now partly filled with iridescent goethite.

The pyrophyllite and andalusite are desirable due to their chemical inertness, high dielectric strength, high melting point and low electrical conductivity. The use of the high alumina minerals decreases the thermal expansion and moisture expansion of the product during high temperature service, provides excellent volume stability and resistance to deformation at high temperatures. Pyrophyllite is used in the ceramic industry in the production of heat resistant products such as electrical insulators.  It is used in soaps, paints and in bleaching powders.  The most familiar use for the mineral is as talcum powder.  North Carolina is a leading producer of raw pyrophyllite in the United States. 

Additional Information:

How did the unique rock form?

What kind of rocks and minerals are in the quarry?

Cross section of Occoneechee Mountain




Want to learn more about the geology of the Eno River area?

You may be interested in A Geologic Adventure Along the Eno River - A richly illustrated publication from the North Carolina Geological Survey.