66 J. L. Campbell—Dufrenite from Rockbridge County, Va. 
of the incrustations and nodules had been long exposed to the 
weather, the fibrous crystals had become changed in color to a 
yellowish brown, so as to resemble in general appearance 
fibrous limonitte—the original structure being preserved. 
The unaltered part of the mineral reduced to fine powder 
was of a light yellowish green color. en heated in a closed 
tube, it gave off water freely ; and small fragments, heated to 
redness for a short time, assumed a bright reddish chestnut- 
brown color when cold. Before the blowpipe, it fused readily 
to black magnetic beads. With the borax bead the reactions 
of iron were well marked, with some indications of manga- 
nese. The mineral dissolved readily in hot hydrochloric acid. 
Tests applied to the solution indicated the presence of ferric 
oxide in abundance, and ferrous oxide in smaller quantities ; 
* 4° . ° « . 
while reactions of phosphoric acid were very decided. 
A subsequent analysis of a choice specimen gave the follow- 
ing results: Specific gravity, 3°382 ; hardness, about 4: 
Phosphorie acid (as pentoxide) Seer tel 
POLPOUN OMI ee ke 6°144 
Ferric oxide 50°845 
Alumina 0°212 
manwanoun UXIGB Gf oe ee ds ek 0°403 
ime 17124 
g c 0°762 
Water lost at red heat 8°531 
Insoluble silica—very fine sand.................------. 07115 
99°897 
ody of the mineral mass is “ dufrenite,” which hitherto seems 
rarely to have given identical results in the hands of any two 
as “South Mountain ”—one of the many primordial broken 
northeast of the same stream. But if the stratum on the sec- 
tion marked lg be conceived to extend nearly to the top of 
