A NATURAL SYSTEM IN MINERALOGY. 71 
beryl, spodumene, black tourmaline, andalusite, topaz and cyanite, as well as various 
phylloids, including tale, muscovite, lepidolite, margarite, phogopite, and ripidolite, are 
not attacked by this reagent. It may be added that datolite, which in the tables we have 
placed among Pectolitoids, appears, from its great condensation and its comparative indif- 
ference to the action of fluorhydric acid, to belong to the Protadamantoids. 
§ 10. Pursuing farther this interesting path of investigation, Mr. Mackintosh has, 
at my suggestion, determined the relative rate of attack, by experiments on equal weights 
of various native silicates reduced to grains of uniform size and exposed to the action of 
Tage VIII.— PROTOPERADAMANTOIDS. 












Es 
SPECIES. | FORMULA. P D VARIE 
| | 
Pargasite. - |(m,al;si,)o, - (mM == Cag.;Mg}.;) -|17.60 | 3.05 | 5.79] C. 
Keïlhauite. (momisltis)on- - = = = =| 02.2) 8.72)| 7... NC: 
Schorlomite. |(caifissiétis)o,yy - - - - - - 21.41] 3.80) 5.63] ? 
Idocrase. - | (cagal,8is)0i)9 - - - - - -  -|19.30|3.40|5.67| T. 
Garnet. - (caalsi,)o, - -~- = = - =/18.75] 3.50) 5.37] I. 
Allanite. - (m,al,si,)o, - (m = cescadfed) |21.67| 4.00| 5.42] C. 
Ægirite. - | (Mesfijsi,.)o,3 - (m,—na,ca,fe,) |19.72| 3.58 | 5.50] C. 
Beryl. - - |(besal:si:)oygy - - - - - -/|14.92) 2.70) 5.52) H. 
Euclase. - |(be,salsgi,)o + laq - - - - -/14.50| 3.10) 4.67] C. 
Arfvedsonite. |(m,f,81,0)05 - (m,—naca,) ~-|19.26| 8.59 | 5.33) C. 
Ardennite. (nT asi) Og la CO 7018162) PRO: 
Axinite. - |(camsi,..bo,.)o, - (m,=al$fiz) |18.11| 3.27 | 5.53| A. 
Epidote. - | (caym,si;)ogt}aq - (m,==al$fiz) |18.38 | 3.40 | 5.40 | C. 
Zoisite. - - (caalsi,)o; - = - - - - -{17.83] 3.35) 5.82] O. 
Jadeite. - |(naalsi,)o, - - - - - - -{16.88] 3.382) 5.08] ? 
Gastaldite. (myaksis)o9 - - - - - - -|17.08| 3.04/5.61] C. 
Glaucophane. | (mgalsis)oi3 - - - - - - -{17.57| 3,12) 5.63} C. 
Prehnite. - | (casalysig)on + 1aq - - - - -|16.66| 2.95] 5.64) O. 
“Acmite. - | (mpfisSi,,)o,3- (mM, = Na}.;feo.;) - [19.50 | 3.53 | 5.52] C. 
Spodumene. | (li,al\sip)o5 - - - - - - -/15.53/3.18| 4.88) C. 
Sapphirine. |(mgalisi)og - - - - - - -|17.16) 3.48) 4.90) O. 
Staurolite. (fe,al,si,.;)0;5 + 42q - - - -|18.45] 3.75} 4.92) O. 
Coronite. - |(my,alsi;)o9 - - - - - - ~|16.86) 3.05) 5.36) R. 
Schorlite. - |(myalsi,jo,, - - - - - - -{16.68/ 5.10) 5.38) R. 
Aphrizite.- | (mjaljsig)o5 - - - - - - - 17.24 | 3.20 | 5.38] R. 
| Indicolite. (mialsis)ony = = = - - - -|16.42 3.08 | b:33 MR, 
limepetiiten= |(aelasin)ons ee 1606) 9100)|/0:851/, IRs 
an excess of dilute fluorhydric acid. This, with a strength of nine per cent., was found to 
dissolve in one hour’s time, of 100.00 parts of albite, 23.00 parts; of petalite, 28.97; of iolite, 
47.34; of orthoclase 43.45 ; and of leucite 66.30 parts ; while of chrysolite but 5.40, and of 
quartz but 1.56 parts were dissolved. Of opal, under similar conditions, 77.68, and of a 
yellowish noble serpentine (specific gravity = 2.532) 80.67 parts were dissolved, showing 
a great susceptibility of these colloid or porodic species to the action of the acid 
solvent. Labradorite and oligoclase are, like the other feldspars, readily attacked, but the 
separation of an insoluble calcium-fluorid was found to be a disturbing factor in quantita- 
