Mr. T. S. Hunt^s Examinations of some Canadian Mina'als. 327 



The mineral has thus a composition entirely different from 

 that before assigned to it, and from the ratio between the oxygen 

 of the silica and the protoxides, evidently pertains to the type 

 Si'' ©^(M'*) of Gerhardt, to which the hornblendes are by him 

 referred. This formula, corresponding to 2SiO'^, 3M0 in the 

 Berzelian notation, better represents the composition of this spe- 

 cies than the formula of Rammelsberg, R'^Si^ or Si^M^O'^. 



Serpentines. — The species described some years since by Dr. 

 Thomson under the name of Retinalite*, was founded upon a 

 specimen of serpentine sent him by Dr. Holmes, from the vi- 

 cinity of Grenville in this province. According- to his analysis, it 

 was a hydi-ated sihcate of magnesia and soda, containing silica 

 40"55, magnesia 18-856, soda 18-832, peroxide of iron and alu- 

 mina "920, and water 20-000. This composition in a mineral 

 having the sensible characters of serpentine seemed anomalous,, 

 and I was therefore desirous of submitting it to further exami- 

 nation. Dr. Holmes had still in his possession a portion broken 

 from the specimen which he sent to Dr. Thomson, and this he 

 kindly placed in my hands. I have also specimens collected by 

 myself at the original locality. It there fills seams, or is diffused 

 though a white crystalline limestone in the vicinity of a dyke of 

 trap, and Ls most abundant nearest the intrusive rock. It is 

 massive, \nthout any trace of crystallization, and has a hardness 

 of about 3-5 (3-75 Thomson). Specific gravity 2-494-2-525, 

 (2-493 Thomson). Other specimens of an olive-green colour gave 

 2-476. Lustre resinous, shining, streak white, colour honey- 

 yellow passing into oil-green and ohye-green, translueent, fracture 



COnchoidal. ,-jih yJ.'(!-Ali'^ '•^--JH:- ' ■. ■■ . .r. -;.;i':o il 



The first analysis is from the original specimen, which was 

 honey-yellow, the second from another specimen of an oil-green. 

 The pttlyerizedmiiiiemL. was dried over sulphuric acidij j;ju ,0^0 

 'nM.'i;T(,((T <)r,8v,; Cl8i.; lAi/nni ,j • . 

 SiKca'. '^'1 fioo-is.-io if^i 7 39.34 

 Magnefeia •JP'^'jyf^f;^' . , 43^0» 

 Peroxide of irori' e/ioijioqjfgor? ■(■i-> 



Soda traces. 



Water 1509 



99-25 99-55 



Another serpentine closely resembling the retinalite, which is 

 found in nodular masses with a calcareous nucleus, imbedded in 

 limestone at the Grand Columet Island, has a specific gravity of 

 2-362-2-381, and a pale wax yellow colour. Its analysis afforded 



* Outlines, &c., voi;i.(^^ 201. 



