Harpers Ferry Quartzite has primary sources along the eastern side of the Fall Line of Virginia near Fredericksburg and along the Rappahannock River. Is reported into northern North Carolina and Harpers Ferry in Maryland.
This appears to be a quartz rich meta arkose from the Harper Formation, Chilhowee Group of Maryland, Virginia, and West Virginia which has primary outcroppings on Short Hill - South Mountain along the Potomac River Gorge.