64 Dr. Thomson m some New Minerals. 



100-24 

 If we suppose the oxide of iron to be combined with alumina, and 

 to be only accidentally present, the constitution of silicite will be 

 7 (AIS") + 2 (Cal. S). 



It is a double anhydrous aluminous silicate. It differs from fuller's 

 earth by containing 2 (Cal. S) instead of 2 Aq. 



5. Gymnite. — To the fifth mineral species which I mean to notice 

 at present, I have given the name of gymnite^ because its locality is 

 the Bare hills west of Baltimore. I got the specimen in my collec- 

 tion from Mr. Alger of Boston, well known for his and Mr. Jackson's 

 excellent geological description of Nova Scotia. 



The mineral was in amorphous pieces, having a very pale and dirty 

 orange colour. It is translucent on the edges; the lustre is resinous. 

 It is very tough, and difficult to break. This makes it difficult to 

 determine the hardness ; but it is softer than felspar. The specific 

 gravity is 2-2165. 



When held in the flame of a spirit lamp, it becomes dark brown ; 

 with soda it fuses into a white opaque bead ; with borax, into a colour- 

 less bead ; with nitrate of cobalt it assumes a rose red colour. 

 Being subjected to analysis, its constituents were found to be 

 Silica, .... 40-16 

 Magnesia, .... 36-00 

 Water, .... 21-60 

 Alumina, with trace of iron, 1*16 

 Lime, .... 0-80 



99-72 

 It is therefore composed of silica, magnesia, and water, and its con- 

 stitution may be represented by the formula 2 (MgS) + MgS 

 + 4 Aq. 



6. Baltimorite. — For the next mineral species which I mean to 

 notice, I am also indebted to Mr. Alger. The specimen was labelled 

 ashestus with chrome, and the locality, Baltimore. On this account, I 

 have given the species the name of Baltimorite. 



The colour is greyish green. The mineral is composed of longi- 

 tudinal fibres, adhering to each other, and has a considerable resem- 

 blance to asbestus. The lustre is silky. The mineral is opaque ; but 

 when very thin, it is translucent on the edges. It is a very little softer 

 than calcareous spar. It does not fuse before the blowpipe, but assumes 



