Description of Edivardsite. 163 



feet crystals, however, are needed than any I have yet seen for de- 

 duchig the incidence of P to the obtuse lateral edge. The diagonal 

 cleavage is almost as perfect as the corresponding cleavage in Silli- 

 raanite. So close is the resemblance between the smaller crystals 

 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. Percival, 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-j>rismatic 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 



