

Prof. B. Silliman, Jr., on some American Minerals. 385 

 Taken -7335 grammes. Yielded 



""" Oxvffcn 



Si -32385=perct. 44151 = 22-940=7 



» ■ * 



Al -31000 " 42-263 19 763 6 



3-290 1 



Mg -05400 " 7-361 2-85 



Na -01270 " 1-731 0-46 



Hand Tl -02590 « 3-532 3146 1 



Loss -00705 " 0-962 



•73350 100-000 



7 atoms silica = 4041-17 =perct. 4486 



6 " alumina = 385400 " 42-78 



3 " magnesias 775-06 n 8-62 



3 " water = 337-44 " 3 74 



9007-67 100-00 



• *# * • • 



R 3 Al 6 Si 7 H*=R3 Si 4- 6A1 Si+3H. 



This formula and constitution are believed to be unknown in 

 any previously noticed species among minerals, and I therefore 

 propose it as new and suggest for it the name Unionite } derived 

 from Unionville, its locality. At present it is a rare substance, 

 but I understand that the place where it was found is to be worked 

 soon for emery, and probably both it and the Euphyllite will be 

 obtained there in abundance. This species was also supplied to 

 me by Mr. Williams of West Chester. 



III. On Monrolite. 



A mineral resembling Worthite. — My attention was called to 

 this mineral by Mr. Wrn. S. Vaux, of Philadelphia, who had re- 

 ceived it from the locality marked " topaz." It somewhat re- 

 sembles pycnite in general aspect, but as will be seen is a very 

 different thing. 



It occurs at Monroe, Orange Co., New York, where it is found 

 *n a quartzose rock with magnetic iron, pink feldspar, black mica, 

 pinite and common garnet. Color green to greenish gray. Struc- 

 ture radiating in sheafs from a centre in groups from an inch to 

 two inches in diameter. Also in single implanted individuals. 

 Cleavage and form of single crystals resembles sillimanite. Hard- 

 ness 7-25 on an angle ; on cleavage face about 6. Gravity 3045, 

 3 "096, 307. Columnar, fibrous. The oblique prisms were not 

 measured, being too irregular. 



B. B. Alone in tube gives off neutral water. Infusible, whitens ; 

 dissolves slowly in carb. soda, readily in borax and in salt of phos- 

 phorus, leaves a siliceous skeleton which reacts slightly for iron. 



Its qualitative assay indicated the presence of silica and alu- 

 mina, with a trace of iron and magnesia. 





