278 A. II. Phillips— Next) Zinc Phosphates. 



The above represents the results arrived at from the analysis of 

 the air-dried sample. The sample dissolved readily in dilute 

 acids to a perfectly clear solution leaving no residue and quali- 

 tative tests revealed do other elements present, except in traces. 

 The analysis yields the ratios of 7Zn0.2P a O t ,.7iH 2 0, or 

 2(Zn 8 (P0 4 ),).Zn(OH) a .6^B[ !1 0, a formula which is very satis- 

 factory, with the possible exception of the water. The water 

 is somewhat variable with the condition of the sample. The 

 crystals are filled with small cavities which contain water as 

 shown under the microscope. Water was determined in 

 another sample which had not been exposed to the air as long as 

 the first sample, with the result that it yielded 13 - 90 per cent. 

 Then a crystal was picked out of the matrix, ground, and the 

 water determined at once with 14r'8 per cent as the result. A 

 portion of this crystal weighing -34S gms. was then tested for 

 loss of water at different temperatures, for comparison with 

 that of spencerite. 

 It lost at 110° 130° 210° 250° 275° Red heat 



5-74,^ 7-24$ 7-93^ 10-05^ 11-35$ 14-71 



The crystals are basic, as is shown both by the high tempera- 

 ture at which a considerable part of the water is given off and 

 by the yellow color of the hot sample, due to the presence of 

 zinc oxide. 



Physical properties. — There are three cleavages parallel to 

 the three pinacoids. Of the three, the brachypinacoidal cleav- 

 age is perfect, that parallel to the macropinacoid less so, and 

 the basal cleavage is imperfect. The specific gravity, as deter- 

 mined on small fragments with methylene iodide, varied but 

 little from 3'2l3. It fuses easily and becomes yellow while 

 hot ; decrepitates strongly in the closed tube, yielding much 

 water. Hardness is about 3'75, scratching calcite easily. 



Optical properties. — QS\foe\\\i% is a pale yellow, almost 

 white, translucent, with a vitreous, though somewhat pearly 

 luster. The double refraction is very weak. Extinction is 

 parallel on all three pinacoidal sections, with the plane of the 

 optic axes parallel to the base. The macroaxis o is the acute 

 bisectrix. Optically negative. 



The small lens-shaped crystals mentioned, as being implanted 

 on the hibbenite crystals, are also found in the solution cavi- 

 ties of the spencerite and represents a secondary mineral, 

 formed from solutions derived from the spencerite. While 

 these crystals have been separated from the other material by 

 means of methylene iodide, the sample was contaminated with 

 considerable calamine. The analysis, however, indicates that 

 they, also, are a new basic zinc phosphate. It is hoped that 

 a pure sample may be separated and the chemical formula 

 reported in the near future. 



Princeton, June 16, 1916. 



