Bchaixeb.] Minerals from iieouu Heights. 



217 



determined, with alunogen, and is tentatively referred to that 

 species. 



Besides the efflorescences of epsomite in the neighborhood, 

 an occasional specimen was met with which, besides giving a 

 test for magnesia, showed also the presence of aluminum in 

 fairly large quantities. It is probably a mixture of alunogen 

 and epsomite. All of the specimens were, however, impure and 

 dehydrated to some extent, so that no analysis was made of any 

 of these aluminium sulphates. 



HEMATITE AND LIMONITE. 



The alteration of pyrite is usually accompanied by the forma- 

 tion of oxides of iron, and both hematite and limonite occur 

 at the mine. The hematite is in the form of a compact red 

 ochre. A specimen gave 10 per cent, of water, which may 

 have been occluded, or the mineral may be classed as tnrgite. 

 The limonite occurs mostly as yellow ochre, although occasionally 

 it is in compact brown masses. 



SUMMARY. 



By the study of the sulphate crystals formed by the 

 oxidation of the pyrite ore, ten new forms are established 

 for pisanite, seven for melanterite and two for chalcanthite. A 

 new sulphate of copper containing seven molecules of water, 

 instead of five, occurs as one of the secondary minerals, to which 

 the writer gives the name boothite. The three minerals,, pisa- 

 nite, melanterite and boothite form an isomorphous series. 



The theory is advanced that all of these hydrous sulphates 

 may be regarded as salts of tetrahydroxyl sulphuric acid, since 

 they apparently contain one molecule of constitutional water. 



In conclusion, the writer wishes to express his thanks to 

 Dr. Arthur S. Eakle, under whose guidance the investigations 

 were carried out. Also to Dr. W. C. Blasdale and Mr. Booth 

 of the Chemical Department, and to Mr. Storch, the superin- 

 tendent of the pyrite mine, grateful acknowledgements are due, 

 for much assistance. 



University of California, 

 April, 1903. 



