486 L. V. Pirsson — Fowlerite variety of Rhodonite. 



expected, considering the degree of accuracy attained in the 

 measurements. 



In the following table, for the sake of comparison the 

 calculated angles as presented by Flink are given in the first 

 column, in the second are the angles calculated from the 

 fundamental measurements mentioned above, and lastly those 

 measured on the fowlerite.* 



Calculated. Measured. 



Flink. Author. 



c a a, 001 a 100 72° 36' 30" *72° 30' 72° 30', 72° 35', 72° 25', 



c a&,' 001 a 010 78 42 30 78 16 



Ma to, 110 ^. 110 92 28 36 92 49 30" 91 45 



to a 6, 110 a 010 45 52 54 45 32 45 33 45 34 



Mac, 1^0 a 001 86 23 50 *86 41 86 40 f87l5 86 20 86 37 



TOaC, 110 a 001 68 44 56 *68 25 68 28 68 24 



k aC, 221 ^ 001 62 22 20 *62 21 62 28 63 15 



Ma a, 110 a 100 43 55 30 44 19 30 43 15 



«Ad, 110 a 100 48 33 6 *48 30 



r aC, 111 a 001 46 9 27 46 41 46 22 f45 20 



n aC, 221-001 74 23 43 74 42 74 02 74 44 74 48 f75 



g A c, 221-001 43 7 23 43 1 1 30 43 15 



e aC, 441 a 001 53 52 53 41 



fi aC, 401 a 001 52 21 20 52 25 52 55 f51 40 53 19 



p aC, 201*001 59 19 58 37 



<p -a, 401a100 25 25 . 25 45 



001 a 445 25 47 26 50 



001a661 58 15 58 37 



001 a 883 48 05 47 38 



In general, it is to be noted that the more exactly a measure- 

 ment could be made, it was found to agree with greater 

 closeness with the calculated one for this variety, than with 

 that given by Flink and this is the only hint we have that the 

 introduction of the zinc has produced any change in the axial 

 ratios and angles. In order to determine this, however, much 

 more exact measurements must be made on better material 

 than is at present to be had. 



In the figures ISTos. 1 and 2 represent the ordinary habit of 

 the larger crystals. Almost invariably they are characterized 

 by a development in the direction of the prism M, 110. Fig. 

 8, however, shows one with a greater development of the prism 



l. 2. 



* Those measurements with a dagger (f) in front are the mean of a series of 

 approximations with a hand goniometer on lusterless faces of very large crystals. 



