Spectroscopic Examination of Silicates. 327 



and quoted in Dana's Mineralogy, 5th ed., p. 374. It con- 

 tained \'0 per cent, of potassa. 



Certain minerals in which we should confidently expect to 

 find no alkalies were examined, and as a confirmation of 

 analysis the negative results have a certain value. Amono- 

 these were a number of woUastonites ; chrysotile and balti- 

 morite from the chrome mines of Lancaster Co., Pa. ; the 

 variety of ripidolite, known as clinochlore, from the ser- 

 pentine quarries of Chester Co., Pa., and the crystallized 

 ripidolites of Texas, Lancaster Co. The crystallized kaem- 

 mererites, a variety of pcnninite, from Texas, likewise save 

 no alkaline spectra. 



The examination of a numl)er of vermiculites was of par- 

 ticular interest, as showing the presence of lithium in all of 

 them, whereas hitherto it had been detected in none. Some 

 of these vermiculitic minerals are varieties of ripidolite 

 more or less altered, others have been made into separate 

 species under the names of vermiculite and jefferisite. But 

 all of these minerals are probably the results of alteration, 

 and it is a curious fact that all of them contain lithium. 

 This may, at a later time, perhaps, assist to explain the 

 causes and manner of those surprising alterations visible 

 along the line of the serpentine ridges of Pennsylvania, 

 New Jersey, and probably elsewhere. Of the vermiculites 

 from the original locality at Milbury, Mass., I had no speci- 

 men to examine, but an exfoliating mineral in bronze colored 

 scales from the chlorite schist bordering the serpentine 

 quarries above Manayunk on the Schuylkill river, con- 

 tained lithium ; the matrix of chlorite schist contained none. 

 Three other varieties of exfoliating ripidolite from Chester 

 Co., Pa., gave similar results. A leek-green variety o-ave a 

 very strong and persistent lithium band ; a bronze colored, 

 a band less positive ; and a light green variety, a faint 

 lithium band. A quantitative analysis of the first gave 0-33 

 per cent, of lithium; of the second a trace, and of the third, 

 none. Another vermiculite, occurring at Texas, Pa., in a 



