658 MINERALOGY 



2. Yields water. 



LIMONITE, Fe 4 3 (OH) 6 ; Yellow, brown to brownish 

 black ; Silky, dull ; H. 5-5.5 ; G. 3.80 ; Inf. ; Mas- 

 sive ; p. 363. 



Gothite, FeO(OH) ; Yellow, brown to brownish black ; 

 Dull; H. 5-5; G. 4.37 ; Inf.; IV; p. 363. 



Xanthosiderite, Fe2O(OH) 4 ; Golden-yellow to brown; 

 Silky, pitchy ; H. 2.5 ; Inf. ; Earthy, acicular. 



Turgite, Fe 4 O 5 (OH) 2 , Red to' reddish brown; Dull; H. 

 5-6; G. 4.14; Inf.; Incrusted. 



a. Fused with soda it yields a sulphur reaction. 

 Planoferrite,Fe 2 (OH) 4 SO 4 .13H 2 O ; Yellowish green ; H.3. 



Compare sulphates of iron, p. 635. 



b. After the separation of iron it shows magnesium ; c, 



p. 567. 



Pyroaurite, Fe(OH) 3 .3 Mg(OH) 2 .3 H 2 O ; Golden-yellow 

 to silver-white ; Pearly; H. 2-3 ; Inf.; G. 2.07 ; III. 



C. Gelatinizes with HCl; p. 591. 



1. Yields little or no water in the closed tube. 



ALLANITE, (Ca.Fe) 2 (Al.Ce.Fe) 2 (AI.OH)(Si0 4 ) 3 ; Brown 

 to pitch-black ; Resinous ; H. 5.5-6 ; G. 3.90 ; F. 2.5 ; 

 V ; p. 468. 



ILVAITE, CaFe 2 (Fe.OH)(Si0 4 ) 2 ; Iron-black; H. "5.5-6; 

 G. 4.05; F. 2.5; IV; p. 472. 



FAYALITE, Fe 2 SiO 4 ; Yellow to dark yellowish green ; 



Resinous; H. 6.5 ; G. 4.32 ; *F. 4 ; IV; p. 450. 

 a. Fused with soda and niter on wire, shows manganese ; 

 b, p. 574. 



Hortonolite, (Fe.Mg.Mn) 2 Si0 4 ; Yellow to dark yel- 

 lowish green ; Resinous ; H. 6.5 ; G. 4.03 ; F. 4.5 ; IV. 



Kenebelite, (Fe.Mn.Mg) 2 SiO 4 ; Gray, brown, green; 

 Greasy; Cl. pinacoidal; H. 6.5; G. 3.95; IV. 



2. Yields water in the closed tube. 



Cronstedtite, H 8 Fe' / 4 Fe" / 4 Si 3 O 2 o ; Black to brownish 

 black ; Cl. basal ; H. 3.5 ; G. 3.35 ; F. 4 ; III. 



Thuringite; Hi8Fe 8 (Al.Fe)8Si 6 4 i ; Olive to pistachio- 

 green; Dull; H. 2.5; G. 3.18; F. 4 ; Compact. 



D. Decomposed in HCl without gelatinizing, leaving a residue of 



silica; d, p. 591. 



1. Fused with soda and niter on wire it shows manganese, 

 b, p. 574. 



