A NATURAL SYSTEM IN MINERALOGY. 
parts of oxygen (or its equivalent) with hydrogen, silicon, boron, aluminium, sodium or 
other metal—is readily calculated from the empirical formula of the species. 
$ 9. Attention has, moreover, been called, in an essay entitled “The Genetic History 
of Crystalline Rocks,” presented to the Royal Society of Canada at the present meeting (May, 
1886) to the indifference of certain silicates to fluorhydric acid, which, as is well known, 
attacks many such compounds, and combines not only with the contained bases but with 
the silica itself. It was therein noticed that, as shown by different observers, zircon, 
staurolite, amphibole, pyroxene and chrysolite, resist more or less completely the action of 
this solvent, so that, as Fouqué and others have found, these silicates may be separated 
from feldspars, and from vitreous colloid or porodic silicates like obsidian—all of which 
are readily dissolved by fluorhydric acid. 
Tage VI.— Zeo.irorps. 

‘al 







SPECIES. FORMULA. 12 DAV: 
Xanthorthite.- | (mahsi:)04 + 2aq - (m—=ce, fe) - - - 2.90 
Hamelite. - -| (m,al,si,)o, +1aq - (m= mg,fe,na) | ....|...|... 
Catapleiite. -|(m,zr,si)09 + 2aq - - - - - - -| 18.09] 2.80) 6.46 
Cancrinite. -| (nagal,,Si.7)0,; + 3¢,Ca,03 +44aq - -| ....| 2.42)... 
Thomsonite. -| (m,al,si,)o, + 23aq - (m=—caïnai) -| 13.58 | 2.38) 6.54 
Gismondite. -| (cayal,Sipso)0gs0t43aq - - - - - | 14.38 | 2.26) 6.36 
Natrolite. - -| (ma,al,si,)o+2aq - - - - - -|15.83 | 2.25) 7.03 
Scolecite. - -|(ca,al;sis)o,, +8aq - - - - - - -| 15.08} 2.40) 6.28 
Mesolite. - - | (m,al,sig)o,) + 3aq -(m—cañna) -| 15.15 | 2.40) 6.31 
Levynite. - -| (ca,al,sig)op+4aq - - - - - -| 14.64} 2.16) 6.77 
Pollucite. - -| (mjal,si,)o,. + 1aq - (m= csjna}) -| 21.46 | 2.90) 7.40 
Analcite. - -| (naaljsi,)o., +2aq - - - - - - -| 15.71) 2.29) 6.86 
Eudnophite. - | (na,al,si,)o,,-+2aq - - - - - -| 15.71] 2.27) 6.92 
Laumontite. - | (caal,sisjo., +4aq - - - - - -|14.68 | 2.80) 6.38 
Herschelite. - | (m,al;si,)o,, + 5aq - (m=najk})- -| 14.76 | 2.06 7.16 
Phillipsite. - | (mjal,si,)o,, +5aq-(m—cañnax) -} 14.41 | 2.20) 6.55 
Chabazite. -| (ca,al,si,)o.,+6aq- - - - - - -| 14.05| 2.19] 6.41 
Gmelinite. -| (m,al,si,)o,, +6aq-(m—cagnai) -| 14.11 | 2.17) 6.50 
Faujasite. - - | (m,al,si,)o,;-+9aq - (m — nazca}) -| 13.45 | 1.92) 7.00 
Hypostilbite - | (ca,al,sis)o,, +6aq - - - - - - - 14.10 | 2.20) 6.40 
Harmotome. -| (m,al.si)0,, +5aq - (m= baypnay'y) | 16.78 | 2.45] 6.82 
Epistilbite. -|(caalsi,)o, +5aq - - = - - -| 1447 | 2.25) 6.43 
Brewsterite. -| (m,al,sij,)o,,+5aq - (m—=srznaz) -| 15.27 | 2.45) 6.23 
Stilbite. - -|(caalsi.)o +6aq - - - - - -| 14.23) 2.20) 6.46 
Heulandite. -| (caalsi,)ot5aq - - - - - -| 14-47 | 2.20) 6.58 
Edingtonite. - | (bajal,si,Jo,+4aq - - - - - -| 17-84) 2.71) 6.58 
Sloanite. - - (cmalsi)os F3aq - - = = =.= 15.31 | 2.44! 6.27 
Forestite. - - (cayalpSi,,)o,,+6aq - - - - “ -| 14.56 | 2.40) 6.06 

Meanwhile, Mr. J. B. Mackintosh, of the School of Mines, Columbia College, New 
York, having tried this acid to distinguish between certain gems, called my attention in 
April, 1886, to the fact that garnet was unattacked by it, an indifference ascribed by me to 
the great condensation of this silicate, which is near that of the adamantoids already men- 



“OOH ASASSCHHFPROORSOHH FASB SOOHH.S 


