300 IF. 1. Schaller — Tfie Al unite- Be udantite Group. 



Goyazite Hamlinite 



Yellowisli, white Colorless, yellowish 



semi-transparent transparent 



uniaxial, positive uniaxial, positive 



tetragonal or hexagonal hexagonal (rhombohedral) 



cleavage, basal cleavage, basal 



H = 5 H = 4-5 



G = 3-26 G = 3-228, 3-159-3-283 

 per cent A1 2 3 + P,0 6 = 65-53 per cent A1 2 3 + P„0 6 = 62 , 8'7 



fuses with difficulty fuses about 4 



Utahite and related minerals. 



On the basis of our present knowledge, utahite, cyprusite, 

 raimondite, pastreite, carphosiderite, and apatelite form a group 

 of minerals which are very closely related. They are all 

 hydrous sulphates of ferric iron with very similar quantitative 

 composition and all occur in hexagonal or rhombohedral scales. 

 The only one of these minerals which has been found in 

 measurable crystals is utahite, for which two values for the c 

 axis have been given, namely 1-1389 and 1-0570. If one 

 remembers that the quality of the material analyzed was of 

 doubtful purity in many cases and that perhaps the analytical 

 methods used were not always of the best quality, the differ- 

 ences in the analytical figures become of minor weight, and 

 one seems almost justified in regarding them as all identical. 

 They may be placed chemically into three divisions, the for- 

 mulas of each of these being as follows : 



I. Utahite 3Fe 2 3 .3S0 3 .6H 2 



TT j Carphosiderite 3Fe 2 O 3 .4SO 3 .10H 2 O 



U - I Apatelite 3(Fe,Al) 2 3 .3S0 3 .9H 2 



( Raimondite 2Fe 2 3 .3S0 3 .7H 2 



III. -] Pastreite like raimondite 



( Cyprusite 4(Fe,Al) 2 3 .5S0 3 .'7H 2 



These different formulas are all very close and, taking into 

 consideration that as far as the published descriptions go, the 

 crystalline form is the same, it seems reasonable to regard them 

 all as identical. It may be noticed that the above formulas are 

 all close to 



3Fe 2 3 .4S0 3 .7H 2 



though to none of them has this formula been ascribed. This 

 formula corresponds to that of a jarosite in which the K 2 is 

 replaced by H 2 0. 



Jarosite = K 2 0.3Fe 2 3 .4S0 3 .6H 2 



New formula = II 0.3Fe O 4SO, .6lI o 



