NO. 2060. WOLFRAMITE, BERAUNITE, AND AXINITE— WHERRY. 509 



ever, with beraunite. The specific gravity, determined by a pycno- 

 meter, varied from 2.850 to 2.920; Dana gives 2.95. The indices 

 of refraction were found to be approximately a and /?=1.78, ^=1.81, 

 extinction straight (elongated parallel to b.), and sign of elonga- 

 tion — . No optical data have been published for beraunite, but Dr. 

 E. S. Larsen, of the United States Geological Survey, kindly exam- 

 ined for comparison a specimen of the variety "eleonorite" (U.S.N.M. 

 Cat. No. 80622) from the type-locality at Giessen, Germany, and 

 obtained the values: «' = 1.775, /?= 1.786, ;-= 1.815, which are essen- 

 tially the same as those above given. 



Two possible explanations of the variation in composition shown 

 suggest themselves. The first, that the law of definite proportions 

 does not hold in this, and other iron phosphates, would be capable 

 of introducing a rather chaotic condition into mineral chemistry, 

 and seems entii-ely improbable. If the mineral were a colloid, bow- 

 ever, the results could at once be interpreted in a second way — that 

 the mineral is an adsorption compound of ferric and manganic 

 hydroxides with phosphoric oxide and water. It is, however, a 

 meta-coUoid, that is, a colloid which has become crystalline without 

 dissolving or losing its soHdity. If, when this crystallization took 

 place, the adsorbed constituents united as well as they could into 

 definite compounds which formed mix crystals (or, as it is often 

 called, solid solution), the results obtained could easily be accounted 

 for. 



The RjOg-.PjOg ratio shown here varies from 1.72:1 in No. 2 to 

 1.93:1 in No. 1, whUe that indicated by the best previous beraunite 

 analyses is 1.50:1, and the best dufrenite analyses, 2.00:1. The 

 simplest explanation of the variation and indefinite ratios shown 

 by the specimens under investigation is that they represent mix 

 crystals (solid solutions) of these two fundamental compounds. The 

 dufi-enite molecule is in excess over the beraunite, although the 

 properties are those of the latter mineral; it might therefore be called 

 dufreniberaunite. 



AXINITE FROM DELAWARE COUNTY, PENNSYLVANIA. 



In the pegmatite cutting the granite gneiss of the Leiper Quarry at 

 Avondale, Delaware County, Pennsylvania, an occurrence of the min- 

 eral axinite has been discovered, certain features of which are so 

 unusual that it has seemed worth while to make it the subject of 

 special study and description. It was in fact at first supposed to be a 

 new mineral, and its true character was only recognized toward the 

 end of the investigation. 



Specimen 1 (U.S.N.M. Cat. No. 87232) consists of three small frag- 

 ments, showing a columnar mineral with a resinous luster, of a pale 

 yellow to salmon pink color, associated with pink microchne, granular 



