274 A. F. Rogers — Collophane. 



On combining these, they yield the following :f 



1. 3 Ca 3 (P0 4 y 0.98 CaCCV 0.01 CaO 3.02 H 2 0. 



2. 3 Ca 3 (P0 4 ) 2 - 0.47 CaCCV 0.46 CaF 2 - 0.03 CaSCv 0.37 CaO 3.05 H 2 0. 



3. 3 Ca 3 (P0 4 ) 2 - 0.97 CaC0 3 - 0.26 CaF 2 -4.45 H 2 0. 



4. 3 Ca 3 (P0 4 ) 2 - 1.03 CaCCV 0.21 CaF 2 -0.25 CaO" 3.02 H 3 0. 



5. 3 Ca 3 (P0 4 ) 2 - 0.46 CaCCV 0.13 CaF 2 - 0.45 CaSCV 0.94 CaO' 0.68 H 2 

 fin computing these ratios magnesium, iron, aluminum, sodium, and potas- 

 sium have been combined with calcium. 



The above may be written in another form : 



1. 3 Ca 3 (P0 4 ) 2 



2. 3 Ca 3 (P0 4 ) 3 



3. 3 Ca 3 (P0 4 ) 2 



4. 3 Ca 3 (P0 4 ) 2 



5. 3 Ca 3 (P0 4 ) 2 



0:99 Ca(C0 3 )- 3.02 H 2 0. 

 1.33 Ca(C0 3 ,F 2 ,S0 4 )- 3.05 H 2 0. 

 1.23 Ca(C0 3 ,F.,)- 4.45 H 2 0. 

 1.29 Ca(C0 3 ,F 2 ,0)- 3.02 H 2 0. 

 1.98 Ca(C0 3 ,F 2 ,S0 4 ,0)- 0.68 H 2 0. 



The ratios vary from 3 Ca 3 (P0 4 ) 2 .CaX to 3 Ca 3 (P0 4 ) 2 . 

 2CaX. 



That these formulae represent the chemical composition is con- 

 firmed by three analyses of collophane of fossil bone with only 

 0.1 to 0.2 per cent of impurities recently made by K. S. Boynton 

 under the writer's direction. On calculation the following 

 formulae are obtained : 



3 Ca 3 (POJ, .0.99 Ca(C0 3 ,S0 4 ,0). 3.03H 9 O 

 3 Ca 3 (POJ 2 .1.48 Ca(CO s ,F 2 ). 2.18H 2 

 3 Ca 3 (POJ 2 .1.78 Ca(C0 3 ,F 2 ). 1.88H 2 



It seems clear that we have here a case of solid solu- 

 tions of calcium carbonate, etc. in tricalcium phosphate. 

 In one of these analyses (No. 5) calcium oxide predomi- 

 nates over calcium carbonate, and Artini 16 has described 

 a ''fluocollophanite'' from Palestine which is near fluor- 

 apatite in composition. The sulphate radical is present 

 in some specimens of collophane and it is probable that a 

 crystalline mineral with the formula 3 Ca 3 (P0 4 ) 2 .CaS0 4 

 will be found some time. Such names as fluocollophane 

 are not advisable. The fine distinctions made with crys- 

 talline minerals, for example, voelckerite, dahllite, etc., 

 are hardly warranted in the case of amorphous minerals. 

 So, then, collophane may be used for the amorphous 

 equivalent of any member of the apatite group, in which 

 the compound 3 Ca 3 (P0 4 ) 2 predominates. 



The Sombrero collophane is almost exactly 3 Ca 3 (P0 4 ) 2 . 

 CaC0 3 and several of the others approach 3 Ca 3 (P0 4 ) 2 .Ca 



18 Abstract in Zeit. f . Kryst. u. Min. lv, 320, 1915. 



