i6o 



NEW YORK STATE MUSEUM 



It will be noted from the above that both (034) and (053) fall in 

 normal series N 3 , the first series being disturbed by but one extra 

 form of normal series N 4 , (047), between the limits J and 3, and the 

 second having no extra form between these limits. Also between 

 these limits, the first N 3 series is complete, and the second lacks 

 but two terms. 



^2 (165). This new form is the first of a series of three brachi- 

 pyramids, all having the same 9 value and constituting the dis- 

 tinguishing characteristic of the occurrence. The faces of this 

 pyramid were fairly prominent on most of the crystals studied, and 

 although somewhat dull gave quite well-defined images of the signal. 

 The form was determined by measurements of the p angle and by its 

 position in zone [101:011:110]. 



ty (166) . This brachipyramid, which was first recorded by Schrauf 1 

 on barite crystals from Pribram, has since been noted by several 

 observers. It was present on a number of the Five Island crystals 

 as a series of small, dull planes, identified by the value of the p angle 

 and by the fact that they lay in zone [011:111], 



^3 (167). This new brachipyramid belongs in the same series as 

 the two mentioned above, and was observed with them on several 

 of the Five Islands crystals as a series of small, dull planes. The 

 planes of (167) were identified by measurement of the p angle and 

 by their presence in the zones [001 : 166] and [165 : on : 167 : 101]. 



The following are the measurements upon which identification 

 of these brachipyramids is based : 



Letters 



Symbol 



Number 



of 

 readings 



Measured 



Cal- 

 culated 



c : ^2 



001:165 

 001:166 

 011:166 

 001:167 



8 

 5 

 4 



58° 21' 



53 12 



9 4 

 48 47 



58° 9 ' 



53 17 



9 14 



48 58 



c: **" 



0: * 



c: ^3 





2 Barite from Black Cape, Quebec 



The specimens which furnished the material for this study were 

 collected in the summer of 19 14 by Mr C. A. Hartnagel of the State 

 Museum staff, at Black Cape, on the north shore of Chaleur bay, 

 in the province of Quebec, Canada. The barite crystals were found 

 in the interior of calcite geodes, the latter being obtained from 



1 Schrauf, A., Ber. Akad. Wien. 1871. 64. 199. 



