ART. 20 



CHLOROPHOENICITE — FOSHAG, BERMAN, GAGE 



pyramid faces than on the dome zone. The lustre of the crystals is 

 vitreous to pearly, the pearly lustre being more pronounced on the 

 front pinacoid face to which the good cleavage is parallel. Some 

 of the larger crystals have a slight iridescent tarnish. 



The plane of the optic axes lies across the needles, that is, it lies 

 in the plane of symmetry. Cleavage flakes show the emergence of 

 an optic axes only slightly off center. The dispersion is strong with 

 p greater than v). Plates showing the emergence of an optic axis 

 have anomalous interference colors characteristic of axes with high 

 dispersion. 2V measured with a micrometer ocular is 83° ±2°. The 

 optical character is negative. The indices of refraction measured 

 by the oil immersion method were found to be as follows: 



a= 1.682 



/3=1.690 



7=1.697 



The specific gravity, calculated from the relation , = k (Glad- 

 stone's rule) is 3.55. 



CHEMICAL PROPERTIES 



The color changes on heating from green to black and the mineral 

 evolves abundant water, the crystal faces becoming rough and porous . 

 Before the blowpipe the crystals become black, coloring the flame 

 a faint pale blue and glow \vith a bright light. The crystals fuse only 

 with difficulty. The mineral is soluble in acids and the solution 

 reacts for arsenic, manganese, and zinc. 



Material for analysis was obtained by carefully picking the clean 

 crystals from the specimen which were then crushed and examined 

 under the petrographic microscope and the sample found to be essen- 

 tially pure. The amount available for analysis was one-quarter of a 

 gram. Upon analysis the following results were obtained: 



Table 1. — Composition of chlorophoenicite 



The analysis yields the formula lORO.As2O5.7H2O, in which RO 

 is essentially manganese and zinc with magnesia, lime and ferrous 



