Seybert^s Analysis of various Minerals. 1 1 3 



Art. XIII. — Analysis of the Tabular spar, from the vicinity 

 of Willsborough, lake Champlain, and of the Pyroxene 

 and Colophonite, which accompany it ; by Henry Sey- 

 BERT, of Philadelphia. 



1. Tabular spar. 



This mineral is white. Lustre, pearly and splendent. 

 It appears to be composed of coarse granular portions inti- 

 mately interwoven ; on a close examination, they exhibit 

 the appearance of hexagonal tables, striated on the surface, 

 easily frangible in the direction of the striae, and have a 

 cleavage in the opposite direction. Fragments highly trans- 

 lucent. Scratches glass, but does not scintillate with 

 steel. Does not phosphoresce when heated.* Specific gra- 

 vity 2,884. Fusible, before the blowpipe, into a transpa- 

 rent colourless vitreous globule. When boiled, with con- 

 centrated nitric acid, it dissolves partially, and yields a so- 

 lution, which precipitates abundantly with an oxalate, or 

 an excess of sub-carbonate of soda. 



Analysis. 



A. 3 grammes of Tabular spar, finely pulverized, were 

 exposed to a red heat, in a platinum crucible, the powder 

 remained colourless, after the calcination the weight was 

 2. 97 grammes, therefore the diminution, due to moisture, 

 amounts to 0. 03 grammes, on 3 grammes, or 1. per 100. 



B. The calcined mineral (A) was heated to redness, du- 

 ring 30 minutes, with 9 grammes of caustic potash, in a 

 silver crucible, the mass when cold was treated with wa- 

 ter and an excess of muriatic acid, the solution was of a 

 light yellow colour, on evaporation it became gelatinous, 

 the dry mass was treated with water, acidulated with muri- 

 atic acid, and again moderately evaporated ; it was then 

 treated with water and filtered, the Silica, remaining on the 

 filter, after edulcoration and calcination, weighed 1.53 

 grammes on 3 grammes, or 51.0 per 100. 



* According to Mr. Hauy, Tableau Cotnparatif, p. 66, the Tabular spar 

 from Dognazka is phosphorescent in the dark when scratched with steel ; 

 Dr. Meade who discovered this mineral in the United States, in 1809, inform- 

 ed me that recent specimens were likewise phosphorescent by friction. 



Vol. v.— No. I. 15 



