376 Scientific Intelligence. 



Combination. P — x (i) P (*). (P ~ ^ (g). £iL±JLiil( r \ 



Fig. 17. Inclination of a on z' = 159° 2'. 



Cleavage, traces parallel to P. Fracture perfect conchoidal. Surface 

 rather uneven. Lustre imperfect metallic, inclining to resinous. Colour 

 dark brownish-black, in thin splinters pale. Streak very pale brown, like 

 peritomous titanium-ore. Opake, in thin splinters translucent. Brittle. 

 Hardness = 5.5 .. . 6.0. Sp. Gr. = 5.838, Allan ; = 5.800, Turner. Not 

 magnetic. 



Observations. — Before the blow-pipe, it loses its colour, and becomes 

 pale greenish-yellow, but is alone infusible. It is entirely dissolved in 

 salt of phosphorus, but some particles remain a long time unaltered. The 

 pale greenish globule becomes opake by flaming, or on cooling, when very 

 much saturated. Before the whole portion has been dissolved, it assumes 

 a pale rose colour in the reducing flame. It has been considered as an 

 Yttro-tantalite, which is not contradicted by the experiments before the 

 blow-pipe. It is described under that denomination in the German Grund- 

 riss of Mohs. Mr Haidinger has given it the name of Feigusonite, at the 

 suggestion of Mr Allan, in compliment to Robert Ferguson, Esq. of 

 Raith. 



It was discovered by Sir Charles Giesecke, imbedded in rhombohedral 

 Quartz at Kikertaursak, near Cape Farewell, in Greenland. The speci- 

 mens to which the preceding description refers are in the cabinet of Mr 

 Allan. Crystals of it had been described by Mr Phillips, and examined 

 before the blow-pipe by Mr Children, under the name of Allanite; from 

 which, however, it is sufficiently distinguished by the tetartoprisroatic 

 form of the latter.— (Mohs, vol. ii. p. 688. Transl. vol. iii. p. 98. Trans. 

 Roy. Soc. Edinb. vol. x. part 2, p. 271.) 



31. Picrosmine, a A T ew Mineral Species. 



Prismatic. P = 151° 3', 120° 0', 67° 59'. Approx. (a : b : c = 

 1 : ^11.00 : N /2.75.) 



Simple forms and combinations not known ; the character of the latter 

 prismatic, as it appears from cleavage. Cleavage, Pr + x (M) perfect ; 

 Pr 4- x (T) less, Pr {*) =117° 49' still less distinct. Least of all P + x 

 (.$) = 126 D 52'. The product of all the faces of cleavage is represented 

 by Fig. 16. Fracture uneven, scarcely perceptible. Lustre pearly, dis- 

 tinct upon Pr + cc , inclining to vitreous upon the other faces. Colour 

 greenish- white, passing into greenish-grey and mountain-green, sometimes 

 also oil-, leek-, and blackish-green. Streak white, dull. Translucent on 

 the edges ... opaque. Very sectile. Hardness = 2*5 ... 3*0. Sp. Gr. = 

 2*660 of a cleavable compound variety, 2'596 of a columnar variety. 



Compound Varieties. Massive: composition granular, strongly coherent. 

 If the composition becomes impalpable, the fracture is earthy. The par- 

 ticles of columnar compositions are very thin ; fracture splintery. 



Observations. Its chemical composition is unknown. Before the blow- 

 pipe it is infusible, but gives out water, becomes first black, then white 

 and opaque, and acquires a degree of hardness nearly = 5-0. It is soluble 



