Intelligence and Miscellanies. 193 



External shape spheroidal, or sub-angular. 



Sfruciure lamellar, cleaving in two directions; at right an- 

 gles to each other, or as nearly so, as the perfection of the 

 planes will allow us to observe. One of these cleavages is 

 effected with greater ease than the other, and presents im- 

 perfect horizontal strioe. The lamellar structure is often in- 

 terrupted by a sub-conchoidal fracture. 



Lustre vitreous, and splendent in the most perfectly cleav- 

 able masses, but glimmering only, on the conchoidal surfaces. 

 Color grey, often with a tinge of blue, and rarely, olive green. 

 Translucent on the edges, and in a few instances, transparent. 



Hardness equal to that of crystallized adularia : the one 

 impressing the other, only when great mechanical violence 

 is exerted. It scratches the crystallized pyroxene of Mussa. 



Specific gravity was determined upon a mass, which be- 

 fore its fracture into two pieces, weighed 6'1 grs. ; the entire 

 mass gave 3*3. and the largest fragment 3*38. Another mass 

 weighing 3*4 grs. gave a specific gravity of 3-90. The mean 

 of the three experiments is 3*259. 



Chemical Examination. 



Before the blow pipe, in small fragments, with the most 

 intense heat that could be urged, it fused with ebullition up- 

 on its thinnest edges into a shining black glass, and the frag- 

 ment became immediately attractable by the magnet. With 

 borax, in powder, it dissolved, forming a greenish transpar- 

 ent glass. With carbonate of soda it entered into fusion, 

 with difficulty, becoming transparent, or nearly so in the full 

 heat of the blowpipe, but immediately turning dark reddish 

 brown and becoming opake on being removed from the 

 flame, and finally changing to white. W^ith microcosmic salt, 

 it dissolves with readiness, and the glass assumes a deep straw 

 yellow color, which on coohng becomes of a paler tinge and 

 contracts a degree of cloudiness. 



1. A small portion of the mineral reduced to the state of 

 an impalpable powder was introduced into a flask upon 

 which diluted muriatic acid was affused. To the flask was 

 fitted a glass tube to deliver over the gas which might be 

 extricated, into a vial containing a solution of acetate of lead. 

 A gentle heat was applied to the flask, when sulphuretted hy- 

 drogen gas made its appearance and the precipitation of 

 the lead commenced. The apparatus was disengaged as 

 soon as it was perceived by the smell (through the means of 



Vol. XVI.— No. 1. 25 



