264 



SCIENCE PROGRESS 



Percentage 

 Composition. 

 Per cent. 



Si0 2 



TiO, 



A1A 



Fe,0 3 

 Feb 



MnO 



MgO 



BaO 



SrO 



CaO 



KO 



Na.,0 



P.0 5 



S 



73'96 



Trace 



13-10 



0-74 

 1-28 



0-04 

 0-18 

 o'o6 

 0-13 

 o'yo 



3'55 

 0102 



0-041 

 0-084 



Molecular 

 Proportions. 



1-2327 



Allotment. 



/"0196 anorthite 

 0089 orthosilicates 

 3222 orthoclase . 

 3438 albite . 

 0088 orthosilicates to 

 metasilicates 

 5294 quartz . 



'1284 



f'°537 



'0573 



"0098 



'0076 



'"0046 



f '0046 



•0184 j -0006 



l'OI32 



•0045 



-0142 



'0044 



{ 



•0013 

 0005 

 0039 



orthoclase 



albite 



anorthite 



corundum 



magnetite 



magnetite 



pyrite . 



metasilicate 



metasilicate 



apatite . 



fluor 



anorthite 



orthoclase 



albite 



apatite 



pyrite 



apatite 



fluor 



Mineral 

 Molecules. 



"0098 



'0537 

 *o573 



•0177 

 ■5294 



"0076 

 •0046 



"0006 



•0020 



'0007 ' 



IOO'I3 



This distribution is carried out in the manner following : — 

 In the first place sufficient lime and fluorine are allotted to 

 phosphorus pentoxide to form apatite, 3(CaO) 3 P 2 3 + CaF 2 . 

 As much lime is then allotted to the remaining fluorine as 

 will form the mineral fluor, while the sulphur and a part of 

 the ferrous iron are united to form pyrite. 



After these minor matters are disposed of, the alumina is 

 allotted to the potash, soda, and remaining lime to form the groups 

 K 2 . A1 2 0„ Na 2 . A1 2 3 , and CaO . AL0 3 respectively. The excess 

 of alumina is represented as forming corundum, although that 

 mineral is, as a matter of fact, not present in the rock. To the 

 ferric oxide the same molecular amount of ferrous oxide is added 



Measured in molecules of P 2 Or,. 



