Wright — Three Contact Minerals. 547 



Chemical Analysis. 



1 la 2 3 4 



Si0 o 26-33 '4359 29*78 28*59 31*40 



Ti() 2 *03 -0004 



A1 2 3 . _ 27*82 *2722 22*02 22*32 22'32 



Fe 2 3 1*43 -0089 3*22 



FeO *50 -0070 1*82 0*37 0*03 



MnO _ -01 -0001 0*50 0*96 



MgO 2*44 -0605 3*88 7*78 10*02 



CaO 39-55 '7050 37*90 36*76 30*92 



Na 2 *21 -0035 0*40 1*17 



K *10 *0009 0*21 0*12 



H 2 1*85 -0103 1*28 



CaS„ 3*25 3*85 



C0 2 none 



100*27 1*5047 99*90 100*18 100*79 



1. Gehlenite, Yelardena, Mexico. E. T. Allen analyst, 

 la. Molecular proportions of 1. 



2. Gehlenite, Monzoni, Rammelsberg, Mineralchem., 1875, 604. 



3. Gehlenite, Falkirk, Sweden. Edg. Jackson in Bauermann, 

 Journ. Iron and Steel Inst., 1886, i, 88. 



4. Gehlenite, Clarence, J. H. L. Vogt, Stud. Slagger, Stock- 



holm, 1884, 138. 



Before the "blowpipe thin slivers of this mineral melt down 

 with difficulty to dark, non-transparent beads, give a pronounced 

 calcium flame reaction and glow intensely. 



In the hand specimens, gehlenite occurs either practically 

 alone except for magnetite inclusions, or together with spur- 

 rite, yellow garnet and calcite. Later veinlets consisting 

 chiellv of calcite were noted occasionally, cross cutting the 

 specimens. 



So far as the writer has been able to ascertain from the avail- 

 able literature, this occurrence is the first recorded for gehlen- 

 ite on this continent. 



Spurrite* 



This mineral, like gehlenite, occurs in granular masses which 

 at first glance might be mistaken for crystallized marble, 

 especially since the cleavage faces frequently glisten in the 

 sunlight like those of calcite. No crystals were observed and 

 the only goniometric measurements possible were made on 

 cleavage fragments. Two cleavages were observed, the one 

 good and the second much less perfect. The reflection signals 

 from these faces were not of equal value and the cleavage 



* Type specimen from contact aureole of Terneras intrusion, Yelardena, 

 Durango, Mexico. 



