164 Report on the Geological Survey of Connecticut. 
mington, Southbury, and at Rocky Hill, Hartford, ignites slowly, 
and burns without flame or odor: it is therefore, rather referable 
to anthracite than to bituminous coal. The coaly matter, oc- 
curring in seams with crystals of dolomite in marly shale at Berlin, 
and in the bituminous shales of Southbury, is compact bitumen. In 
many instances when freshly taken from the quarry it is semi-fluid, 
or only so much inspissated as to form what is called the elastic 
bitumen, or mineral-caoutchouc. It burns with a white flame and 
much smoke.” 
“ Plumbago.—A plumbago-mine was worked to some extent, 
seventy or eighty years ago, in the northwest corner of Ashford, on 
land then. owned by Mr. Apontsan Backus. It bad been pre- 
viously opened, but at what period is not now known. At the time 
here mentioned however, a number of tons of plumbago were ob- 
tained. The mine was worked in the manner of a quarry, and an 
excavation made of considerable extent. This is now completely 
filled up with stones, which have been carted thither from the con- 
tiguous fields ; a road also passes quite across one end of the trench. 
The rock of the vicinity is gneiss, analogous to that embracing the 
plumbago at Sturbridge, which is about six miles in a northeasterly 
direction from this place. And such is the conformity of this direc- 
tion with that of the stratification of the gneiss, as almost to justify 
the opinion, that the Ashford and the Sturbridge deposits of plum- 
bago have a connexion with each other. This suggestion is the 
more probable from the fact, that the gneiss rock is similar at both 
places, and eaniaias scales of the mineral in question at several inter- 
lee 
. points, 
A number of persons from Colchester, in 1813, from the loose 
materials thrown out eighty years ago, obtained in a short time a 
wagon-load of plumbago. 
‘¢ Another depository of plumbago is in the western ein of Corn- 
wall, on a mountain nearly three hundred feet high, and situated 
directly upon the eastern bank of the Housatonic river. It is the 
property of Mr. Gipeon P. Paneman. The rock is gneiss, and 
wherever it comes into view on its western slope, this mineral may 
be detected as entering more or less into its composition,—some- 
times in large proportion, forming a plumbaginous gneiss. A trench 
has been exeavated at an elevation of about one hundred and filty 
feet above the river, nearly six feet wide and pene acer into & 
rock containing sib taeuium of piambagn 
