1917] Eakle: Minerals Associated with Crystalline Limestone 345 



defined crystal boundaries, apparently hexagonal in outline. No 

 wilkeite occurs in it, but it is evidently an altered product, presum- 

 ably from wilkeite. Analyses show that it is principally a hydrous 

 calcium silicate with some of the silica replaced by the phosphate, 

 sulphate and carbonate molecules. It is a new hydrous silicate of 

 calcium having small amounts of the other oxides in place of the silica 

 and the name crestmoreite, after the locality, is proposed for it. 



The mineral is compact snow-white with vitreous to dull lustre. 

 H = 3. G = 2.22. It fuses quietly and easily to a slightly vesicular 

 glass. It is very easily soluble in acid, leaving some flocculent silica, 

 while most of the silica goes into solution. Some of the lime can be 

 extracted by boiling water. 



The earthy opaque material is not adapted to good optical deter- 

 minations. It has parallel extinction, positive elongation, low bire- 

 fringence and /3 = 1.590 ± .005. 



Analyses of different samples of the mineral were made, all of them 

 showing phospbates and sulphate in the substance. Some of the C0 2 

 determined is due to calcite, which penetrates the mineral in thin seams 



SiO, 



36.12% 



38.30% 



34.42% 



CaO 



42.71 



41.20 



43.54 



P.O.-, 



2.38 



3.50 



3.50 



so 3 



2.42 



1.25 



2 24 



CO, 



1.16 







Ign. 



14.98 



15.17 



16.24 





99.77 



99.42 



99.94 



These analyses correspond approximately to the formula : 



20H,CaSiO, . Ca 3 (P0 4 ) 2 • CaS0 4 • CaC0 3 + 10ILO, 



and this requires the composition : 



SiO, 35.23% 

 CaO 41.10 

 P 2 5 4.17 

 S0 3 2.35 

 C0 2 1.29 

 ELO 15.86 



If crestmoreite were a clear crystallized mineral like the wilkeite, 

 ere would be no doubt that the phosphate, sulphate, and carbonate 

 belonged to it and should be reckoned in its formula ; but its earthy 

 structure and composition show that it is changing to a calcium 

 silicate, and it is quite within reason to assume that the three acid 

 radicals are small portions of those in the original wilkeite, which 



