Virginia. 
117 
appear to be muscovite (sericite), quartz, chlorite, kaolin, pyrite, carbonate, rutile, 
and carbonaceous matter. This is a superior slate, but is less crystalline than that of 
Arvonia. It is used exclusively for roofing, having been found less well adapted for 
mill stock. 
About 1£ miles northeast of the Williams Brothers quarry slate was prospected 
nineteen years ago on the Thompson property. This lies on a small tributarj of 
Otter Creek, which flows into the James 1J miles downstream from Snowden. (See 
fig. 13.) The thickness exposed is 20 feet. Bedding strikes N. 53° E., dips 20° SK; 
cleavage is nearly horizontal. Joints strike N. 38° E. and dip 20° W. This slate 
closely resembles that of the Williams Brothers quarry both in its external and 
microscopic characteristics and i L q i onerousness. 
Contour interval 50feet 
Fig. 14.— Map of slate prospects in Fauquier County, Va. Slate prospects arc shown by round dots. 
Warrenton, Fauquier County. — There are several prospects in the neighborhood of 
White Sulphur Springs on the Rappahannock, 6 miles southwest of Warrenton, to 
[which Rogers referred/' from which roofing slate was obtained as early as L837. 
|(Seemap, fig. 14.) 
The following data afford some indications as to the geological relations: About \\ 
miles south of the Springs and 200 feet east and as far west of the road to Routsville 
there are outcrops of muscovitic quartzite with grains and pebbles of blue quartz up 
I to one-fourth inch across. These beds have an apparent east-west strike and a gentle 
southerly dip. A little north of this quartzite slate crops out and continues north- 
ward for 2 miles to near the ''colored church." Its cleavage strikes N. 25°-30° E., 
but the slate three-fourths of a mile south of the Springs, at the river, strikes about 
a Op, eit., p. 460. 
