NO. 2145. NOTES ON ALUNITE, P8IL0MELANITE, ETC.— WHERRY. 83 



the proper name for the series. Unfortunately, however, the name 

 gummite (Dana, 1868), a contraction of uranogummite (Breithaupt, 

 1847), has been applied to a hydrous oxide of uranium of totally 

 different composition and relationships. Furthermore, the members 

 of the series under discussion are not characteristically gum like, so 

 that the name gummite is not an appropriate one for it. Hitchcockite 

 is next in point of date, having been proposed by Shepard in 1856. 

 It is therefore recommended that the isomorphous series of the gen- 

 eral formula R'o0.8H20.3AL.03.2P.05, or K'oH,[Al(OH),]e(P03)4, 

 with E'=K, Na, |Ca, 4Sr, |Ba, |Pb, iCe, etc., be named the hitch- 

 cockite group. The names goyazite and hamlinite could then be dis- 

 carded in favor of strontiohitchcockite, gorceixite of bariohitchcock- 

 ite, and so on; the salts containing the phosphoric oxide in alunite 

 would be kaliohitchcockite and natrohitchcockite. 



After the constituents of the alunites and hitchcockites are sub- 

 tracted, there remain all the FeoOg and SiOj, together with a little 

 K2O, Na.O, H2O, and ALO3 (Column 6). The first is undoubtedly 

 present as a stain, and may be disregarded; the others are prob- 

 ably united in clay-like substances. The ratio of AlgOg: Si02=l:3 

 approximately, which would indicate a clay of the cimolite group. 



It is therefore concluded that the alunite from Texas consists of 

 about 51 per cent kalioalunite, 33 natroalunite, 4 of a potassium alumi- 

 nium phosphate for which the name kaliohitchcockite is suggested, 

 and 2 of the corresponding sodium compound, natrohitchcockite, ad- 

 mixed with some 10 per cent of a clay (cimolite). 



SODIUftl-BEARING ALUNITES FROM CALIFORNIA. 



Another lot of alunite was received from Mr. Charles Muck of Cali- 

 fornia, the locality being stated as a prospect pit in the Funeral Kange 

 Mountains, near Death Valley, California (U.S.N.M. Cat. No. 87529) . 

 It is similar to the preceding in certain respects, but differs in the 

 presence of a considerable excess of sodium over potassium, as 

 brought out in the description, w^iich follows. 



PHYSICAL PR0PE21TIES. 



Color : White ; specimens from near the surface stained red by iron 

 oxides. 



Luster : Dull, like chalk. 



Structure: Compact (cryptocrystalline) ; fracture subconchoidal. 



Hardness: 2|- (material from 60 feet beneath surface); ^ (that 

 from near the surface of the ground). 



Density : 2.63. 



Optical properties: Under the microscope, appears as confused 

 minutely crystalline aggregates; colorless; mepn refractive index 

 1.585±.b05; double refraction .01. 



