

I. 



P 2 5 



34-90 



FeO 



17-13 



MnO 



34-51 



CaO 



0-63 



H 2 



13-18 



Quartz 



0-13 



142 = -246 



= 1-00 = 1 



12 =-238 ) 





71 = -486 \ 



•735 = 2-99 = 3 



56 = -Oil ) 





18 = -132 



= 2-98 = 3 



212 Brush and Dana — Mineral Locality at Branchville. 



better than what we had had before, and also since the compo- 

 sition — though in fact fully established — may have appeared 

 to some anomalous, in view of its failure to correspond with 

 that of scorodite and strengite in the degree of oxidation of 

 the manganese and in the amount of water. The new analysis 

 by Wells fully confirms the former one made by him, only 

 differing in the larger percentage of ferrous iron present.* 

 This analysis of a carefully selected portion with a specific 

 gravity of 3*204, gave : 



II. 



13-18 



100-48 



The formula is hence E 3 (P0 4 ) o + 3H 2 0, and if K=Fe : Mn — 

 1:2, this requires P 3 G 5 34-64^ FeOl7'56, MnO 34-63, H„0 

 13-17=100. 



Fairfieldite. 



Fairfieldite appears among the specimens recently obtained 

 not infrequently, and in a form much fresher and purer than 

 that *in which we had it before. It is usually in foliated 

 masses intimately associated with reddingite and fairfieldite,. 

 and hardly less so with hureaulite. The color varies from 

 white to yellowish or greenish white ; it is usually perfectly 

 transparent and the luster is very brilliant, varying from 

 adamantine to pearly according to the surface on which it is 

 viewed, the latter on the surface of perfect cleavage. A 

 tendency to crystallization is at times apparent but no crystals 

 suitable for measurement have been found, which is to be 

 regretted since the early results left much to be desired. An 

 analysis of the perfectly fresh mineral has been made by Wells. 

 This agrees with those of Penfield previously published ; the 

 amount of iron is less and that of the manganese greater, but 

 it is worthy of note that the ratio of 2 : 1 for Ca : Mn+Fe is 

 still maintained. f The analysis of pure material having a 

 specific gravity of 3*07 is as follows : 



* The earlier analysis gave FeO 5-43, MnO 46-29. 



f It is interesting to call attention here to the identification of fairfieldite by 

 Sandberger at Rabenstein, Jahrb. Min., i, 185, 1885. It is also worthy of note 

 that a new hydrous phosphate of ferrous iron and calcium, near fairfieldite but 

 with 2£H 2 0, has been recently named messelite by Muthmann (Zs. Kryst., xvii, 

 93, 1889); like fairfieldite it is triclinic. Furthermore the brandtite of Norden- 

 skiold is Ca 2 Mn(As04)2 + 2H 2 0, corresponding exactly to fairfieldite, CEfv. Ak_ 

 Stockh., 489, 1888, Groth, Tab. Ueb. Min., p. 80, 1889. 



