80 Localities of Minerals. 



the lustre is resinous. It may be scraped by the knife, although it 

 scratches glass. It is very brittle, with an imperfectly conchoidal 

 fracture, and exists in botryoidal concretions and amorphous masses, 

 traversed by irregular fissures. Specific gravity from 2.19 to 2.21. 

 Before the blowpipe it loses color, and the point of a slender frag- 

 ment is fused with difficulty into a white enamel. With salt of phos- 

 phorus or borax, a large proportion of the mineral fuses easily into a 

 colorless transparent glass. Mr. Allen of this city analyzed it, and 

 after having carefully verified his results, found it to consist of 

 Silica, _____ 43, 



Magnesia, _ _ _ _ 30,5 



Alumina, - - - - - 2. 



Water, _ - _ - - 24. 



Loss, ----- .5 



100. 

 The magnesia does not seem to exist in a quantity equal to a definite 

 proportion, but there appears just water enough to form with the 

 silica a " hydrate" consisting of an atom of each. 



9. Precious serpentine, of a lively green color is found at the same 

 locality as the last. 



10. Compact ashestus, of a dull green color and translucid, with 

 fibres, as usual, rigid and sharp ; same locality. 



11. Flexible ashestus, pure white, in very soft delicate fibres, ir- 

 regularly disposed, (the var. cotonneux of Haiiy,) occurs in granular 

 limestone, on the York turnpike, sixteen miles from Baltimore. 



12. Graphite, lamellar, occurs in gneiss, three miles east of the 

 1 7 mile stone on the York turnpike, and also in limestone, fifteen 

 miles from Baltimore, on the same road. 



13. Pyritous copper, (a mineral which on account of its value to 

 the arts is always worthy of being noticed,) occurs in small quantity 

 seven miles from this city, on the Baltimore and Ohio rail road, in 

 a rock composed of quartz, imbedded in compact felspar, (porphy- 

 ry?) ; the rock also embraces small grains of magnetic oxide of iron. 

 Pyritous copper also exists in granite, in several places on the above 

 rail road, from nine to fifteen miles from town, but no vein has yet 

 been discovered. 



14. Iron pyrites, in large crystals, {dodecaedre of Haiiy,) is found 

 in limestone, twelve miles from the city, on the York turnpike. 



