194 Description and Analysis of the [Sfcpt, 



Gmelin found it most abundant in the lava called peperino, below 

 the town called Marino, in the neighbourhood of Rome. It occurs 

 in a rock along with green mica, augite, and a white coloured 

 mineral, which from the analysis of Gmelin appears to be a variety 

 of leucite. 



The colour of hauyne is Prussian blue, passing into beryl blue, 

 through sky blue. 



Gmelin found only one specimen crystallized in an imperfect 

 octahedron. It is almost always imbedded in the rocks in the state 

 of grains with sharp angles. In some rare cases only can a single 

 cleavage be observed in it. 



Its fracture is conchoidal, and it breaks into fragments having 

 sharp edges. 



Lustre, splendent and vitreous. 



It is always translucent. 



Its hardness is such that it easily scratches glass ; but does not 

 strike fire with steel. 



It is easily frangible, and may be reduced with facility to powder. 

 Powder whitish. 



Its specific gravity, according to Gismondi, is 3*333 j according 

 to Necrgaard, 3*100 ; according to Gmelin, 2*833. 



It docs not phosphoresce when scratched with a knife. It 

 becomes electric by friction, according to Haiiy, and the electricity 

 is negative. 



Before the blow-pipe it melts with difficulty into an opake bead, 

 full of air bubbles. With borax it melts into a transparent topaz 

 coloured bead. When put into muriatic acid it becomes opake, and 

 loses its colour. When thrown into that acid in the state of powder 

 it emits the odour of sulphureted hydrogen gas, and gelatinizes. 



To subject it to a chemical analysis it was necessary to obtain it 

 separate from the other minerals with which it is usually mixed. 

 This was a task attended with considerable difficulty, and took 

 Gmelin up a full week before he could procure a sufficient quantity 

 of the pure mineral for his experimental investigation. The fol- 

 lowing was the way in which his chemical analysis was conducted : 



A. 



o. — 0*47625 gramme (7*355 grains troy) of hauyne in grains 

 were put into a glass tube, and surrounded with live coals. Vapour 

 of water was immediately given out, which did not alter the colour 

 of paper dipped into acetate of lead. The tube being heated till 

 pome of the grains adhered to it, the weight of the hauyne was 

 found reduced to 0*473 gramme (7*305 grains) ; but its colour and 

 transparency were not altered. 



/.—The same mineral being exposed for half an hour to a strong 

 fire in a platinum crucible, the grains adhered a little to each other, 

 and to the crucible. Many of the particles were not altered, but 

 Borne acquired a blackish blue colour, and at the same time lost 

 their translucence. By this means the weight was reduced to 



