Wells and Penfield — Herderite from Maine. 115 



ing nearly neutral water in a closed tube. The latter reaction 

 is entirely different from that of the Stoneham herderite, which 

 gives off very acid water and etches the glass decidedly. 

 Before the blowpipe in the platinum forceps it turned white, 

 sprouted and fused at about 3 to a white enamel, coloring the 

 flame very pale green. Only a few fragmentary crystals could 

 be found which were suitable for measurement. The crystals 

 had the habit shown in the accompanying figure. They were 

 attached so that only the faces at one 

 extremity of the macro-axis were 

 developed and were grouped in nearly 

 parallel position but with the basal 

 planes slightly divergent. 



The forms which were observed are : 

 c, 001,0; m, 110, I; re, 331, 3 and q, 332, § 



The basal planes were irregular and yielded no satisfactory 

 reflections of the signal, while m and q were small and fre-' 

 quently wanting. All of the faces except c were usually 

 striated. 



The measurements which were made are given below. The 

 calculated values are derived from the axial ratio established by 

 Prof. E. S. Dana* from the Stoneham herderite. 



Calculated. 

 15° 26' 45° 6' 



103° 24' 

 22° 33' 

 17° 9' 



Herderite was not suggested to us by the preliminary exami- 

 nation, and the measurements showed such a close relation to 

 the angles of childrenite, that we fully expected the mineral to 

 be some new variety of the latter, possibly a beryllium chil- 

 drenite. It was not till the results of the quantitative analysis 

 were obtained that we became aware of the true character of 

 the mineral. 



The similarity in crystalline form between childrenite and 

 herderite is as follows : 



n a n, 



331^331 = 45° 7' 



*45° 10' 



n *n, 



331 ^.331=*102° 22' 



103° 7' 



ris-m, 



331 A 110= 22° 14' 



22° 53' 



n^q, 



331^332 = 16° 50' 



16° 32' 



Childrenite. 



Corresp 



onding forms on herderite. 



b, 010, i-i 





c, 001,. O 



101, l-i 





m, 110, I 



p, HI, 1 





n, 331, 3 



s, 121, 2-2 





q, 332, f 





Childrenite a: 



b:c = -7780: 1 : -5257 



Herderite in corresponding position a: b: c = - 7752 : 1 : '4929 



The axial ratio of the herderite was derived from the angles 

 marked by asterisks in the above table of measurements. The 



* This Journal, III, xxvii, 229. 

 Am. Joue. Sci.— Third Series, Vol. XLIV, No. 260.— August, 1892. 



