186 



PHYSIOGRAPHY. 



Sodalite Soda-Nitre. 



2. Before the blow-pipe, Lapis-lazuli melts with difficulty into a glassy 

 globule, which is first of a bluish tinge, but soon becomes white. The 

 compact varieties melt more easily, and with a slight effervescence. It 

 is dissolved with considerable effervescence by borax, and forms with it 

 a clear globule. If previously burnt and reduced to powder, it loses its 

 color, and forms a jelly with acids. Haiiyne melts into a vesicular glass, 

 and loses its color. It effervesces if melted with glass of borax, and 

 forms a transparent globule, which becomes yellow on cooling. Soda- 

 lite, before the blow-pipe, melts with intumescence and the develope- 

 mentof air bubbles, into a colorless, glassy globule : with borax, it melts 

 with difficulty, and only when added in small proportion. Spinellane is 

 infusible, whether alone, or with additions. 

 3. Analysis. 



4. Lapis-lazuli has been brought from Lesser Bucharia, Thibet and 

 China. It has lately been found at Lake Baikal in Siberia, in veins with 

 Iron Pyrites, Feldspar and Garnet. Hatt.yne occurs at Albanoand Fres- 

 cati near Rome, among the products of Vesuvius; also in the neighbor- 

 hood of Puy de Dome, on the Lake of Laach, in the quarries of Nieder- 

 meunich, and in several other places near Andernach, partly imbedded 

 in pumice. Sodalite is found in West Greenland, in a bed in mica-slate, 

 from six to twelve feet thick ; and is accompanied by several species of 

 Augite-Spar and Feldspar, as well as by Zircon anl Eudyalite. It occurs 

 likewise among the minerals ejected by Mount Vesuvius. Spinellane 

 is found on the shores of Lake Laach, with Feldspar, Hornblende and 

 Magnetic Iron-Ore. 



5. The variety Lapis-lazuli is cut into various ornamental articles, as 

 ring stones, snuffboxes, &.c. It is manufactured into a very costly pig- 

 ment, called Ultramarine. 



SODA-NITRE. Rhombohedral Natron-S*alt. 

 Primary form. Rhomboid. Pon P =106 33'. 



