Notices of some Minerals. 337 



in the hundred of protoxide of iron ; while in the American 

 mineral there is only 2*1 per cent. Hence, I conclude, 

 that protoxide of iron is not an essential constituent of 

 anthophyllite. As the lime and alumina are wanting alto- 

 gether in one of the specimens analyzed, they cannot be 

 essential constituents. The great difference in the amount 

 of the water and its absence in one of the specimens renders 

 it unlikely that it enters into the chemical constitution of 

 anthophyllite.' Hence, I am disposed to conclude, that 

 anthophylle, if it could be obtained free from all foreign 

 matter would be an anhydrous bi-silicate of magnesia re- 

 presented by Mg S 2 . 



Schiller spar on the contrary is a hydrous bi-silicate of 

 magnesia or Mg S 2 + Aq. 



We need not be surprized after this, that schiller spar is 

 specifically lighter than anthophyllite, and that there exists 

 a certain resemblance between the two minerals. 



IV. — DEWEYLITE. 



I got a small specimen of this mineral from Dr. Holmes; 

 but unfortunately, he forgot to specify its locality, and 

 merely stated, that it had been analyzed in America, and 

 that its constituents were 



Silica, ... 40 



Magnesia, . . 40 



Water, ... 20 



100 



The specimen constituted an amorphous mass about double 

 the size of a pigeon's egg. 



Its texture is granular, and its colour a light yellowish 

 white. Fracture splintery. . 



Translucent on the edges. Lustre resinous. Easily re- 

 duced to powder. 



Hardness 2-5. Specific gravity 2-2474. 



Before the blowpipe per se, it becomes white and opaque. 

 With carbonate of soda it fuses into a bead having quite 

 the appearance of enamel, white while hot, but assum- 

 ing a red tint on cooling. With borax, fuses with slight 

 effervescence into a transparent colourless bead. With bi- 

 phosphate of soda it does not fuse either in the reducing 



vol. m. z 



