Phosphate Tiock in Tennessee. — Safford. 261 
described by W. D. Matthew from ;i pegmatite vein at South 
Lyme, Conn.* 
EXPLANATION OF PLATES. 
Plate VIII. 
Fig. 1. Weathered surface of gneiss showing the "augen." 
Fio. 2. View of a quarry excavation in the great pegmatite vein on 
farm of P. H. Kinkel (marked B on map). 
Plate IX. 
Fig. 5. Lenticuhir feldspar "auge," sliowing at the left end pmaller 
portion which has been sheared off. 
Fig. G. Map of "augen"-gneiss area. 
A NEW AND IIVIPORTANT SOURCE OF PHOS- 
PHATE ROCK IN TENNESSEE. 
By James M. Safford, State Geologist. 
Much interest has been created recently in middle Tennes- 
see by the discovery of a new source of available phos])hate 
rock in large quantities. This new source is one whollv dif- 
ferent from that yielding the now well known rock of Swan 
creek in Lewis and Hickman counties, Tennessee. They are 
of very different geological horizons. The rock of Swan creek 
is Devonian ; the one to be described is Trenton. That is a 
true rock itself ; this is a residuum after the leaching of a 
rock. The rock is found in workable bodies over a wide area, 
including, it may be, fifteen or twenty square miles of surface. 
In small quantities, in isolated pieces or blocks, washed out 
of the soil, it is found in all the counties of middle Tennessee, 
showing outcrops of the geological horizon to which it be- 
longs, as, for example, in Davidson county and within the 
very corporate limits of Nashville. 
The centre of the present workings and interest is in the 
town of Mount Pleasant, in the southern part of Maury coun- 
ty. Here the phosphate is found, after stripping off the soil, 
in banks from three to eight feet in vertical thickness. Half 
a dozen companies are busily engaged in getting it out. 
From 200 to 300 hands are at work, and where a few weeks 
ago everything was quiet, now all is bustle and excitement. 
The rock is light yellowish or grayish, of an open, spongy 
structure, and occurs in layers or plates of various thickness 
from an inch to six inches or more. The layers are found 
*School of Mines Quarterly, vol. xvr. p. 232. 
