348 University of California Publications in Geology [Vol. 10 



The analyses of riversideite correspond pretty closely to the formula 

 15H 2 CaSi0 4 • 15CaSi0 3 • CaS0 4 • Ca 3 (P0 4 ) 2 + 5H 2 0, which requires: 



Si0 2 



42.00% 



CaO 



44.43 



S0 3 



1.87 





3.31 



H 2 



8.39 





100.00 



Disregarding the phosphate and sulphate it appears that the silicate 

 formed is a combination of the basic orthosilicate and the metasilicate, 

 and a formula to express the mineral may be written 6H 2 Ca 2 Si 2 0.-H 2 0. 

 This requires : 



8i0 2 47.43% 



CaO 44.27 

 Constitutional H.,0 7.111 

 Crystallization fLO 1.19 



100.00 



The optical properties of riversideite kindly determined for the 

 writer by Mr. E. S. Larsen are: 



a = 1.595 ± 0.003, Parallel extinction. 

 y — 1.603 ± 0.003. Z parallel to fibers. 



The name riversideite, after the county in which it occurs, is proposed 

 for this new hydrous lime silicate. 



The water content of a mineral is always subject to different inter- 

 pretations; and it is not always possible to differentiate between 

 hydroscopic, crystallization and constitutional water. Both of these 

 new minerals might be interpreted as simple hydro-wollastonites. 



Crestmoreite CaSi0 3 ■ ELO 

 Riversideite 2CaSi0 3 • H 2 



Clinochlore. — Small pale green flakes of elinoehlore were found in 

 the vesuvianite-masses at the Commercial Rock quarry. 



Apatite. — Specimens of greenish blue apatite in granular form asso- 

 ciated with green diopside and white wollastonite in white calcite were 

 obtained from the quarry, but it does not appear to be an abundant 

 mineral and no crystals of it have been collected. 



Aragonite. — Some of the lime carbonate has subsequently crystal- 

 lized into the orthorhombic form. It occurs sparingly as fibrous and 

 foliated thin layers interspersed with layers of quartz and calcite. 



