1917] Eakle: Minerals Associated with Crystalline Limestone 347 



Biversideite, a New Mineral. — Some of the masses of vesuvianite 

 contain narrow seams of a white fibrous mineral which has similar prop- 

 erties to crestmoreite but with only half as much water, and it does 

 not occur as an alteration of wilkeite, at least not as a direct alteration 

 in situ. The mineral occurs in compact fibrous veinlets in the crevices 

 of the massive vesuvianite and has a silky luster resembling satin spar. 

 H = 3. G = 2.64. Fuses at 2 to a white glass. Easily soluble in 

 dilute acid leaving flocculent silica. 



The mineral is a fibrous crystallization from the solutions carrying 

 the altered wilkeite or crestmoreite and the analyses show that a lime 

 silicate with a ratio CaO : Si0 2 equal to 1:1 is, like crestmoreite, the 

 principal constituent with small amounts of the phosphate and sul- 

 phate present. In this case also the P 2 3 and S0 3 are hardly to be 

 considered as belonging to the mineral. 



Analyses of the fibers gave : 



Mean 



Si0 2 



41.29% 



41.22% 



41.26% 



CaO 



44.62 



44.55 



44.58 



P 2 5 





3.84 



3.84 



S0 3 



1.84 





1.84 



H 2 



8.05 



8.17 



8.11 



99.63 



The water determination gave 



At 102° 



0.80% 



150 



1.00 



250 



1.37 



Eecl heat 



7.77 



Blast 



8.05 



This water analysis would indicate that it is mainly constitutional, but 

 it is a difficult matter to construct a basic formula for the mineral 

 that is satisfactory. The simplest formula to express the composition 

 of riversideite is 2CaSi0 3 -H 2 0. It may be likened to okenite with 

 its basic hydrogen replaced by calcium : 



Okenite (H 2 Ca) Si 2 0„ . ILO 

 Biversideite Ca 2 Si 2 0„ . ILO 



The formula 2CaSiO a • H„0 requires : 



Si0 2 48.00% 

 CaO 44.80 

 H 2 7.20 



