212 Defcription offomt new FoJJth, 



X. PETALITE. 



The colour mod frequently occurring is reddifli, and in feme inftancea greyifti-white. 

 Its internal luftre is ordinary and glittering, now and then with a little fplendor, and in 

 that cafe of a faint appearance of mother-of-pearl. The edges are a little tranfparent. 

 Specific gravity rather above 2.620. It cuts glafs and is itfelf fcratched by feld-fpar. It 

 Hardly ftrikes fire with Heel. It occurs in lumps of a fine and alfo of a rather coarfe ag- 

 gregation. Its texture is foliated or fcaly. The lamelljc are very minute, throughout 

 ftrongly concreted with each other. Their crofllng is but fingle. The fragments of the 

 crofs fradture are angular, amorphous, and not very fharp in the edges. It is broken 

 with great facility, and eafily reduced by grinding into a fubtle, white, rough, and dry 

 powder. When one piece is rubbed againft another, it emits a 'faint fmell refembling 

 quartz. When treated alone with the blow-pipe it is infufible, without change of fcolour 

 or luftre. With borax it produces a white, tranfparent, vitreolis globule, and with micro- 

 cofmic fait a yellowifh-white pearly glafs, full of fine air-bubbles. With nitric acid-it 

 does not effervefce, whether in the ftate of grains or of powder, but a portion is gradually 

 diflblved by that acid. Petalite is found near Utoen, Sala, and Fingrufan, near Nyakc- 

 perberg, in Sweden. 



XI. CHRYOLITE. 



Colour fnow-white. Luftre faint, like a weak fplendor of mother-of-pearl. Very 



tranfparent. Specific gravity 2.9698. It fcratches calcareous fpar, but is itfelf fcratched 



by fluor-fpar. It may be readily broken in pieces, and is rather foft. It yields a very 



fubtle, white powder, of a foft feel, which, if moiftened with water, becomes tranfparent. 



This foflil feels dry, and is cold, like feld-fpar. Its texture thick and broad foliated, with 



an irregular roughnefs, like water that has been fuddenly congealed to ice. Its lamince arc 



flraight, and their crofling threefold. The parts feparatcd by fplitting, when entire, are of 



a cubical form. The aggregation of its integrant parts is fuch, that the junfture of two 



is always covered by a third, fuper-impofed like bricks, which originates from the circum- 



ftance, that two croflings are ftraight and of the broad foliated kind, while the third is 



partly laminated, partly broken, partly uneven. Before the blow-pipe chryolite fufes even 



before ignition, like ice melting without efFervefcence ; and it yields a fnowy-white opaque 



pearly mafs, which by a ftronger heat becomes rough, full of bubbles, and. depreffed in the 



middle, being alfo c^uftic in that ftate when put on the tongue, and poflefied of a tafte 



(imilar to that of borax. When heated with borax, this foflil is fufed to a pellucid glafs, 



which, however, upon cooling is opaque and white. When fufed with pot-afh in a filver 



crucible, it turns to a white porcelanic mafs ; which, w,hen diflblved in diftilled water, and 



precipitated by means of nitric acid, yields a white, tranfparent pafty mafs, which after 



(leiiccation may be fufed again in the fame manner a& the crude foflil. In the nitric and 



muriatic 



