156 PHYSIOGRAPHY. 



Brittle. Hard (it scratches quartz slightly, BREIT- 

 HAUPT). Sp. Gr. = 2-52 from Spechtshausen ; 

 = 2-40 from Hungary, BREITHAUPT. 



Before the blowpipe it is almost infusible, only the edges 

 become covered with a sort of enamel. It is said to be 

 very nearly related to obsidian in respect to its composi- 

 tion. It occurs at Glashiitte near Schemnitz in Hungary, 

 imbedded in pearlstone, and at Spechtshausen near Tharand 

 in Saxony, imbedded in pitchstone, both varieties of em- 

 pyrodox Quartz. It was first distinguished by Mr BREIT- 

 HAUPT. 



SPINELLANE. 



Spinellane. JAM. Syst. Vol. III. p. 549. Man. p. 331. 

 Spinellane. PHILL. p. 127. 



Tessular form, the dodecahedron, sometimes com- 

 bined with the hexahedron. PHILL. Grains. 

 Cleavage, the dodecahedron, imperfect. Fracture 

 conchoidal, uneven. 



Lustre vitreous, inclining to resinous. Colour 

 greyish-black, passing into ash-grey and brown. 

 Sometimes a whitish play of light parallel to the 

 faces of the hexahedron. Translucent ... opake. 



Hardness = 5-5 ... 6-0. Sp. Gr. = 2-282. 



Before the blowpipe it is infusible, whether alone or 

 with additions. According to KLAPIIOTH, it consists of 

 Silica 43-00. 



Alumina 29-50. 



Lime 1-50. 



Soda 19-00. 



Oxide of Iron 2-00. 

 Sulphur 1-00. 



Water 2-50. 



