636 MINERALOGY 



Dietrichite, (Zn.Fe.Mn)Al(SO 4 ) 4 .22 H 2 ; Dirty white 

 to brownish yellow ; Silky ; Fibrous. 



Ilesite, (Mn.Zn.Fe)SO 4 .4H 2 O; Green to white ; V. 

 d. Shows magnesia ; c, p. 567. 



Knoxvillite, (Fe.Mg)[(Fe.Cr.Al.)OH] 7 (S0 4 )8.5 H 2 O ; 

 Greenish yellow ; IV. 



Botryogen, (Mg.Fe)(Fe.OH)(SO 4 ) 2 .7 H 2 0; Hyacinth- 

 red ; H. 2-2.5 ; G. 2.09 ; F. 4.5 ; V. 

 - e. Shows aluminium ; 6, p. 568. 



Halotrichite, FeAl 2 (S0 4 ) 4 .24 H 2 O ; Yellowish white; 

 Silky ; F. 4.5-5. 



Voltaite, Fe 3 (Fe.OH) 2 (Fe.Al) 4 (SO 4 ) 10 .14 H 2 0; Green- 

 ish black; Resinous; H. 3 ; G. 2.79; F.I. 

 /. Contains iron as the only base. 



Reacts for ferrous iron, but not for ferric. 1 



MELANTERITE, FeSO 4 .7H 2 0; Apple-green; Vitre- 

 ous; H. 2; G. 1.9; V; p. 539. 



Contains both ferrous and ferric iron. 1 



Roemerite,Fe"Fe'" 2 (SO 4 ) 4 .12 H 2 O; Light to dark brown ; 

 H. 3-3.5; G. 2.15; F. 4.5; VI. 



Contains ferric iron only. 1 



Coquimbite, Fe 2 (SO 4 ) 3 .9 H 2 O ; White, yellowish ; Vit- 

 reous; H. 2; G. 2.11; III. 



Quenstedtite, Fe 2 (SO 4 )3.10 H 2 O; Reddish violet; Vit- 

 reous; H. 2.5; G. 2.11; V. 



Ihleite, Fe 2 (SO 4 ) 3 .12 H 2 O; Orange-yellow; Vitreous; 

 H. ?; G. 1.81; F. 4.5; Botryoidal. 



COPIAPITE, Fe 2 (FeOH) 2 (SO 4 ) 5 ,17H 2 O; Sulphur-yel- 

 low; Pearly; H. 2.5; G. 2.10; F. 4.5-5; V. 



Castanite, (Fe.OH)SO 4 .3iH 2 O ; Chestnut-brown; Vit- 

 reous; H. 2.5; G. 2.12; F. 4.5; V. 



Amarantite, (Fe.OH)S0 4 .3 H 2 O ; Orange to brownish 

 red ; Resinous ; H. 2.5 ; G. 2.28 ; F. 4.5 ; VI. 



Utahite, 3 (FeO) 2 SO 4 .4 H 2 O ; Orange yellow ; Silky ; 

 F. 4.5 ; III ; Tabular. 



Fibroferrite, (Fe.OH)SO 4 .4|H 2 ; Pale yellow; Silky; 

 H. 2-2.5; G. 1.85; Fibrous. 



1 Ferrous iron is detected by adding potassium ferricyanide to the cold solu- 

 tion, when a Prussian blue precipitate will form ; no precipitate is formed in a solu- 

 tion of ferric salts. 



To detect ferric iron a drop or two of ammonium sulphocyanate is added to the solu- 

 tion, when if any ferric iron is present, the solution will assume a deep blood-red color. 



