69 



anisotropic phosphate. The former of these, a light yellow en- 

 crusting form, returned the following composition : — 



100-00 



100-00 



The second column is a readjusted statement of the analy- 

 sis after subtracting the silica present as sandy impurity. 



On calculation, this result is found not to represent any 

 definite molecular combination, nor was it expected that any 

 such could be deduced after the foregoing petrological obser- 

 vations. It is evidently a mixture of several substances, whose 

 exact nature cannot be determined. 



The Second variety occurs in depressions on the surface 

 of the rock, and masses 20 cms. thick were obtained. It is 

 found as an aggregation of tiny globules about 2 mms. dia- 

 meter, appearing yellowish-brown on broken surfaces. Frac- 

 ture, smooth. Hardness, 5'5. Lustre, dull. In sections 

 under the microscope the spheres are seen to be composed of 

 aggreg^ated doubly-refracting matter of a yellowish-brown 

 colour. An indistinct radial arrangement is observable 

 especially towards the outer margin, where it is also usually 

 of a somewhat lig-hter tint. A little foreign sandy matter 

 is present. Double refraction, probably about 0*023. Re- 

 fractive index, much above quartz. 



99-82 100-00 



The second column is a re-statement of the analysis, after 

 deducting 36*72 per cent, of sand. 



