Description of Edwardsite. 163 
fect crystals, however, are needed than any I have yet seen for de- 
ducing the incidence of P to the obtuse lateral edge. The diagonal 
cleavage is almost as perfect as the corresponding cleavage in Silli- 
manite. So close is the resemblance between the smaller erystals 
above alluded to and Zircon, that on first inspection I mistook them 
for that species. 
The Edwardsite occurs disseminated through Bucholzite in gneiss 
at the falls of the Yantic in Norwich, Connecticut. The Bucholzite 
is here considerably abundant, forming apparently a small bed through 
which are dispersed also individuals of red feldspar, black mica, and 
more rarely small crystals of blue corundum. ‘The variety of Bu- 
cholzite is intermediate in the size of its fibres between that of 
Chester, Conn. (the Sillimanite,) and that found at Chester, near 
Philadelphia, and denominated Fibrolite. 
Having discovered the mineral above described, while occupied 
along with my colleague, Dr. Percivat, in the geological examina- 
tion of the state, I have thought proper to name it in honor of his 
excellency Henry W. Edwards, the governor of the state; since the 
survey was first recommended by his Excellency, and is still in pro- 
gress under his administration. Its place in the natural arrangement 
of minerals is obviously within the genus Tungstic Baryte, and its 
systematic name as hence arising, and connected also with its system 
of crystallization, will be the Hemi-prismatic Tungstic Baryte. 
ANALYSES. 
Qualitative examination. —28 centigrammes of the mineral, in the 
state of an impalpable powder, were heated to whiteness in a platina 
crucible, whereby it lost 1.5 centigrammes in weight. Another por- 
tion was treated with sulphuric acid in a glass tube, without occasion- 
ing any perceptible corrosion of the glass. 
The mineral was next examined for phosphoric acid, of the pres- 
ence of which a strong indication was mentioned in the chemical de- 
scription of the species above given. 11 centigrammes of the igni- 
ted mineral were mingled with thrice its weight of carbonate of potassa 
and heated in a platinum crucible for fifteen minutes. The mixture 
swelled up, became grayish white, porous, and suffered imperfect 
fusion. Dilute acetic acid was added to the mass : a copious, heavy, 
reddish white powder remained undissolved. ‘To the clear acetic 
solution, acetate of lead was added, which occasioned a dense white 
precipitate. Nitrate of silver produced a copious yellow precipitate 
