158 



of Lime, among Quartz, and decomposing Feltsparj 

 whence the rock itself is often called Apatite, the old 

 name for Phosphate of Lime. Abundance of Oxide of 

 Tin often accompanies it. This is a variety of Talc, agreeing 

 with that called Chlorite in every external character except 

 colour, which instead of being green is that of cream. 



The lower specimen has the colour most usually allotted 

 to Chlorite, which is undoubtedly to be attributed to a 

 large adventitious mixture of Iron, which at the same time 

 renders it easily fusible. 



Mica and Talc seem to have the same forms in their 

 Crystals, but they are never by any means so large or well 

 defined in Talc. These Crystals are remarkably soapy or 

 greasy to the touch, particularly if bruised. The laminae are 

 very easilv broken, and are apt to divide into minute greasy 

 scales ; which property has rendered this fossil an ingre- , 

 dient in cosmetics. The white varieties are difficultly fusible. 



White Talc analysed by Hoepfner was found to contain: 



Silex 50 



Magnesia . . . . 44 

 Argil 6 



100 



Chlorite by Vauquelin : 



Silica 26-0 



Argilla 18*5 



Magnesia 8*0 



Oxide of Iron 43*0 



Muriate of Soda and Potash 2*0 



Water 2*0 



Loss 0-5 



100-0 



