ORDER VII. EMPYRODOX QUARTZ. . 337 



4. EMPYRODOX* QUARTZ. 



Indivisible Quartz, 6th 9th subsp. JAM. Syst. Vol. I. 

 p. 283. Fusible Quartz. Man. p. 214. Pearlstone. 

 Pitchstone. Pumice. Obsidian. PHILL. p. 112. 130. 133. 

 135. Obsidian. Pechstein. Perlstein. Bimstein. WERX. 

 Hoffm. H. B. II. 1. S. 191. 202. 208. 213. Pechstein. 

 Obsidian. Perlstein. Bimstein. HAUSM. II. S. 430. 

 431. 433. 435. Pechstein. Obsidian. Perlstein. Bims- 

 stein. LEOXH. S. 13?. 138. 141. 143. Petrosilex re'- 

 sinite. Lave vitreuse obsidienne, perle'e, pumice'e. 

 HAUY. Traite, T. IV, p. 386. 494. 495. Feldspath 

 re'sinite. Traite', 2de Ed. T. HI. p. 101. 



Regular forms unknown. Grains.-f- 



Cleavage none. Fracture conchoidal, sometimes 

 highly perfect, sometimes less distinct. Surface, 

 the larger grains uneven and rough, the smaller 

 ones smooth. 



Lustre vitreous and resinous. Colour, black, 

 brown, red, yellow, green, grey, white ; none of 

 them bright. There occurs a distinct velvet- 

 black. Streak white. Faintly transparent ... 

 translucent on the edges. 



Hardness = 6-0 ... 7-0. Sp. Gr. 2-395, Obsi- 

 dian from Iceland ;= 2-212, Pitchstone from 

 Meissen. 



Compound Varieties. Massive : composition gra- 



* From e^cn/^a?, belonging to fire, and S|, the opinion ; ac- 

 cording to the opinion of many, produced by fire. 



f In the Phil. Trans. 1816, p. 77- Dr BREWSTER has shewn 

 that the rounded masses of obsidian from Ascension, and from 

 Japan, possess the structure of unannealed glass, and therefore 

 appear to have been cooled from a red heat. H. 



VOL. II. Y 



