( 

 Wiiliamsburgh Mineral, 175 



cially to the variety called spargelstein, or asparagus stone, 

 as it is formed at Cap de Gate, in Murcia, in Spain. 



The characters which I have remarked in the^Williams- 

 burgh mineral, are — that it is electric by heat and friction, in- 

 fusible per se, but loses its colour and becomes white ; with 

 borax it apparently melts, at least the globule obtained is 

 white, and transparent, and to the eye homogeneous. It 

 scratches rock crystal when rubbed on a smooth surface of 

 that substance, and is as easily scratched by the Haddam 

 beryl, and by topaz of Brazil. The fracture of the perfect 

 crystals is both ways conchoidal ; the lustre is shining and 

 vitreous in a high degree, both in the natural surfaces and in 

 the fracture. 



The crystal, whose colour is a delicate straw yellow, is a 

 prism of six sides, remarkably regular, with slight longitudi- 

 nal truncations of the solid lateral edges, thus giving the rudi- 

 ments of a prism of twelve sides ; the sides are not striated, 

 but reticularly indented, as if by the mica of the gangue. 

 The specific gravity is 3.2, the thermometer being at65*Fah. 

 the specific gravity of the beryl is 2.67, of chrysolite 3.4, of 

 chrysoberyl 3.08, of phosphate of lime from 3.02 to 3.21. 

 The Wiiliamsburgh mineral phosphoresces in the dark ; on a 

 shovel heated red hot, it emits a yellowish light. 



January 1825. — Since the above notices were penned,! have 

 received from Mr. Dwight, other specimens in their gangue ; 

 some are massive and some crystallized, the colours are gen- 

 erally shades of pale green, or greenish white ; in a few in- 

 stances nearly apple green. I extracted from the gangue the 

 greater part of a large crystal, split nearly through the diago- 

 nal diameter, which was more than an inch in length, and that 

 of the external sides was almost three-fourths of an inch — 

 the specific gravity of this piece, whose weight was 168 grains, 

 is 3.43, the fracture less conchoidal and more approaching to 

 foliated than that of the specimens described above; the 

 phosphorescence was distinct and beautiful, and one end of 

 the crystal was terminaied, by a flat plane, at right angles to 

 the sides ; the other end was broken. 



Notwithstanding the points of resemblance between the 

 Wiiliamsburgh mineral and phosphate of lime, it seemed dif- 

 ficult to assign to that species, a substance which scratched 

 quartz ; and satisfied with that trial, I neglected to apply the 

 pointof the knife. Learning, however, from Dr. Porter, that 

 Mr. Nuttall is disposed to regard the Wiiliamsburgh mineral 



