Vol. 5] Eakle. — Notes on Some California Minerals. 233 



No. 1 of the Santa Ana Tin Mining- Company in Trabuco Canon, 

 Orange county, and were found about two hundred and fifty feet 

 below the surface in an old Oregon pine tie which is partly sub- 

 merged six months of the year. The tunnel is in black slate 

 which carries some sulphide and the walls of the mine are coated 

 with minute crystals and incrustations of sulphates and carbo- 

 nates. The potassium sulphate has not hitherto been recognized 

 as a mineral species, so this occurrence classes it as a new mineral. 

 The name Arcanite has however been applied to the potassium 

 sulphate and artificial crystals have been measured. 



The crystals are thin plates tabular to c and are pseudo- 

 hexagonal by twinning on the unit prism. Plate 20, fig. 10 shows 

 the appearance. 



The forms observed were : 



c (001) 



s (112) 







o (111) 



e (102) 











Measured 



Calculated 



(001) 



(111) 



— 55°48' 



56 c 



21' 



(111) 



(111) 



— 67 20 



67 



18 



(111) 



(111) 



— 48 37 



48 



52 



(001) 



(112) 



— 36 12 



36 



54 



(111) 



(112) 



— 19 30 



19 



27 



(111) 



(110) 



— 48 50 







The faces were in general dull, and c gave only a bright spot 

 of light, so that accurate measurements could not be made from 

 this face. The o faces were better and gave good reflection. The 

 s faces were always mere lines. Besides these faces, the dome, 

 probably e (102), was present, but it was so rough that only an 

 approximate measurement could be made. 



Transmitted, May, 1.908. 



Date of Issue, November 28, 1908. 



