W. JFrazier — Axinite from Bethlehem, Penn. 



a:6:c=l: 1-5564 : 0-47657. 



There does not seem to be as great a similarity in habit be- 

 tween calamine and datolite as there is between axinite and 

 datolite. 



With regard to the chemical composition of these minerals, a 

 quite evident analogy appears to exist between the formulas of 

 calamine and of datolite. 



From an experiment of Herr Fock in Groth's laboratory it 

 appears that calamine contains no water of crystallization, aa it 

 remained unchanged at a temperature of 340° C, and yielded 

 water only at a red heat. Groth therefore classes it among the 

 basic silicates with a quantivalent ratio of 3 : 2.* The 

 formula of calamine is H 2 Zn 3 Si0 6 . That of datolite is HBCaSiO, 

 with the same quantivalent ratio. 



With regard to axinite the analogy is by no means so clear. 

 Eammelsberg's formula for it is ^ 2 K 6 R 3 Si B 32 . This would 

 make it a unisilicate. It appears to me unlikely, however, that 

 the close resemblance in crystallization between axinite and 

 datolite is a mere accidental coincidence. The balance of prob- 

 ability is in favor of the conclusion that this morphological 

 resemblance is due to some similarity (however obscure at pres- 

 ent) in chemical composition. 



I would not be understood as proposing the adoption of a 

 new position for the crystals of axinite. The position and funda- 

 mental form similar to those adopted by Dana for datolite have 

 been employed in this paper simply to bring out more clearly 

 the resemblance to datolite. This resemblance is, however, quite 

 evident in Miller's position also, and, as far as axinite alone is 

 concerned, this latter position is. I think, decidedly the best yet 

 proposed. It combines the following advantages. The axes of 

 two of the most prominent zones of the crystal coincide with 

 two of the crystallography axes, to which also are parallel the 

 most common striations of its planes. The three pinacoids, the 

 two fundamental hemi-prisms, three of the fundamental ictarto- 

 pyramids, the hemi-maerodomes, 1-7 and —1-7, and the herm- 

 brachydomes, 1-V and 1-i are all represented by common Iv oe« 

 curring planes. The parameters of the planes in general are 

 simpler than when referred to any other fundamental form and 

 axial system, not excepting those of Schrauf. There is no 

 great departure from a right angle in any of the angles between 

 the axes. Finally it brings into evidence the resemblance to 

 * Tabellarische Uebersicht der Mineralien, 2d ed., p. 84. 



