266 Lieut.-Col. Yorke on Browti Iron Ore, 



Fig. 1. 



gong' 

 g on h 

 c on h 

 g on e 



Fig. 2. 

 MonM' 



W. Phillips 

 130° 40' 

 117° 50' 

 121° 45' 

 129° 30' 



Levy f. 

 95° 14' 



P. I. Yorke. 

 130° 27'. 

 114° 46'. 

 121° 34'. 

 129° 26'. 



P. I. Yorke. 



96° 0' 

 115° 42'? 

 114°? 



g on I' . . . 



g on i . . . 



The most brilliant and perfect planes 

 are g ^. 



Quantitative Analysis, 



1. 100 parts lost by ignition 10, and left undissolved, when 

 acted on by muriatic acid, 2*61 of silica. 



2. 12*16 grs, of picked crystals free from quartz yielded — 



In ] 00 parts. 



Silica 0035 0*28 



Water 1*225 10*07 



Red oxide of iron . . . 10*89 89*55 



Oxide of manganese . . 0*02 0*16 



12*17 10006 



Excess . . 0*01 

 The silica obtained is probably an admixture only ; abs- 

 tracting the silica, the following gives the result of experiment 

 compared with theory : — 



In 100 parts. 



Fe,03 = 

 HO 



Atomic 



Weight. 



80 



Experiment. 



Theory. 

 89*89 



9 = 10-11 10*10 



This formula (FcgOg + HO) agrees with that obtained by 

 Kobell from substances designated as nadeleiseneiz, goethite 

 and lepidokrokite % : the first is a name given by Breithaupt 

 to the crystals found in the neighbourhood of Bristol, which 

 have been described by W. Phillips ; the specimen examined 



* Crystals from the neighbourhood of Bristol. 



f Crystals from Botallack, Cornwall. 



X Jnnales des Mines, 3d Ser. vol. xi. p. 493. 



