Genth and Penfield — Contributions to Mineralogy. 203 



positive double refraction. Some of the original material, 

 given us by Mr. Mackintosh for comparison, appears to be 

 identical with this in every respect except that it occurs in 

 radiating prismatic crystals reminding one of wavellite. Hard- 

 ness = 2-5 Specific gravity = 2*517 and 2*578. 

 The analyses of the purest mineral gave : 





I. 



II. 



III. 



IV. 



Mean. 



Molecular 



ratio 



H 2 



so 3 



■" I 6296 



63-58 



11-62 

 51-27 



12-15 

 51-33 



11-89 

 51-30 



0-66 

 0-64 



6 

 6 



Fe 2 3 



... 17-32 



17-20 



17-30 



17-30 



17-30 



11 



1 



CaO . 



0-22 



Dot clet'd. 













Na 2 

 K 2 . 



... 1963 

 0-16 



J- 2001 



20-15 





19-95 



0-32 



o 









Mackintosh's analysis 









for 



comparison. 



11-34 



50-25 



17-23 



18-34 



ALO 









0-43 



Si0 2 , 



etc. 



insol 



uule 



2-00 



100-29 



agreeing with the formula: 3Na 2 S0 4 . Fe 2 S 3 12 + 6IJ 2 0. 



Calculated 



H 2 11-56 



S0 3 --- 51-39 



Fe 2 3 17-13 



Na 2 19-92 



99-79 



Mr. Mackintosh states that his mineral lost at 110° C. 5-| mole- 

 cules of water. The material above analyzed when exposed in 

 the state of a fine powder for two hours at 100° C. lost only 

 0-28 per cent (0-72 gram lost 0-0020 grm.). 



4. Utahite. ? 



Among the minerals, collected by Messrs. Geo. L. English 

 & Co., at the Mimbres Mine near Georgetown, New Mexico, 

 were very minute, microscopic brownish white, apparently 

 hexagonal scales, which had the appearance of Utahite. 



They were mixed with a very large quantity of quartz, van- 

 adinite and descloizite. After the vanadates and other impur- 

 ities were dissolved out by dilute' nitric acid, the hexagonal 

 scales remained behind in a pretty pure state, but mixed with 

 a considerable quantity of quartz. The material thus obtained 

 was divided into two portions, weighing together 2792 grm. 



0*1983 grm. gave 31*82 per cent quartz; deducting this, the 

 loss by ignition in the other portion was 26*85 per cent and 

 the ferric oxide, 55*10 per cent. 



0*0809 grm. gave 2903 per cent quartz, and after deducting 

 this the balance gave 27*16 per cent of S0 3 and 56*49 per cent 

 Fe,0.. 



