Oct. 4, 1921 watson: lazulite 389 



The formula derived from the column of ratios in table 1 is that 

 given in the standard texts for the mineral, except that CaO is usually 

 not expressed : 



(Fe, Mg (Ca)) O . AI2O3 . P2O5 . H2O 

 withFeO:Mg(Ca)0 = 1 :5, FeO: CaO = 1 : 1, and MgO: CaO = 4: 1. 



When compared with analyses of lazulite from other localities 

 the Georgia mineral shows a high percentage of CaO (3.30 per cent), 

 the largest reported in any analysis of the mineral of which the writer 

 has found record. The analysis of lazulite from North Carolina 

 quoted by Dana'' shows no CaO. With two exceptions, Georgia and 

 North Carolina, analyses of lazulite thus far published represent 



TABLE 1. Analysis of Lazulite III 



I II " . 



P2O0 38.25 40.61 286 1 



AI2O3 33.92 36.02 353 1.2 



FeO 3.99 4.24 59] 



MgO 9.08 9.64 241}- 1.3 



CaO 3.12 3.30 59 j 



H2O 5.83 6.19 343 1.2 



Si02 6.05 



100.24 100.00 

 Sp. G 2.958 



I. Lazulite collected by Thomas L. Watson from Graves Mountain, Lincoln County, 



Georgia. J. Wilbur Watson, analyst. 



II. Analysis I with the Si02, which represents admixed quartz, deducted, calculated 

 to 100 per cent. 



III. Ratios from II. 



foreign localities, in which CaO is indicated as being either absent or 

 present in quantity of less than 1 per cent. The only exception found 

 by the writer is an analysis of lazulite quoted by Dana^ from near 

 the mouth of Churchill River, Keewatin, Canada, in which CaO 

 is given as 2.83 per cent. Based on CaO content, published analyses 

 of lazulite, most of which are old, would group the mineral under (o) 

 calcium lazulite, apparently the less frequently occurring variety, 

 to which the mineral from Graves Mountain, Georgia, and Keewatin, 

 Canada, belongs; and (6) essentially calcium-free lazulite which 

 includes the more common variety of the mineral represented by 

 analyses from many European localities. 



OTHER OCCLTRRENCES OF LAZULITE IN THE UNITED STATES. 



Lazulite occurs both as crystals and as massive granular to compact 

 material in quartz veins and in metamorphic rocks, especially quartz- 



• E. S. Dana. Op. cit., p. 799. 

 ' E. S. Dana. Op. cit., p. 799. 



