112 



Sjögren further establishes the formula: 

 (3) {SbO,),É,Tif\^ 



where the fluorine is combined with titanium ; here the amount 

 of basic ingredients is far too large to correspond to the 

 common composition. 



According to Flink M chalcolamprite and endeiolite have 

 respectively: 



and ÈNb,_0^(OH}o + RSiO^ 



With regard to the four minerals: steenstrupite, erikite, 

 britholite, and epistolite the composition is more differing from 

 the common one, and upon the whole very complicate. 



According to Bøggild-) the steenstrupite has the following 

 composition : 



Sil 2 0., ^R^,R;Éi 2 • 4 (P . Л"е )0,В . CaF,_ •AH,_0 



that is to say most nearly as a metasilicate with an orlophos- 

 phate ; as the former is found in by far the greatest amount 

 the deviation from the common composition is not very great. 

 According to what has been stated in the preceding the 

 erikite has the following composition: 



8 SiOo • A F,_0^ • 1 'R,_ 0, ' È0 • Z È.,0 • \\ H^O. 

 If the water is not included in the formula, the remaining 

 part may almost correspond to a compound of an ortosilicate 

 with an ortophosphate. By a combination of groups of hydrox- 

 yle with the trivalent metals so as to get R^{OH)^0 in stead 

 of R^O.^ a combination of a metasilicate with a metaphosphate 

 may be produced, but it is very uncertain whether the water 

 occupies such a position in the molecule; the resemblance with 



') Medd. om Grönl. XXIV. pp. 164, 169. The formulae are erroneously 



given as RNb.O^F^ ^ RSiO^ and RNb,0, {OH),-^ RSiO,. 

 ') Medd. om Grönl. XXIV. p. 213. 



