ANORTHTTE. 71 



Before the blowpipe it is easily fusible, intumesces, and 

 is converted into a white enamel. According to BERZE- 

 LITJS, it consists of alumina, the phosphoric and fluoric 

 acids, and lithia, in greater quantities than any other mineral. 



It has hitherto been found only at Chursdorf near Penig 

 in Saxony, where it occurs in granite, along with rhombo- 

 hedral Tourmaline and prismatic Topaz. It was first dis- 

 covered to be a particular species by Mr BBEITHAUPT. 



ANORTHITE. 



FELD-SPAR. 



Anorthit G. ROSE. Gilberts Annalen der Physik. 1 823* 

 St. 2. p. 173. 



Tetarto-prismatic. Simple forms and combinations, 

 also the regular compositions exactly similar to 

 those of Albite, p. 255., represented in Figs. 

 84-87. Dr ROSE gives the following measure- 

 ments of the angles. 



I on M =122 2'. y on P (over x) = 9S 29'. 



Ton I = 120 30'. P on M (over *) = 85 48'. 



Ton M =117 28'. P on M (opposite) = 94 12'. 



Pon T = 110 57'. s on M = 115 20'. 



* on P = 128 27'. P on = 133 13'. 



Cleavage perfect parallel to P and M ; none paral- 

 lel to T. Fracture conchoidal. Surface of T 

 more smooth than of I. 



Lustre pearly upon cleavage planes, vitreous in 

 other directions. Colour white. Streak white. 

 Transparent ... translucent 



Brittle. Hardness = 6-0. Sp. Gr. = 2-763, mas- 

 sive ; = -656 small crystals, apparently not en- 

 tirely free from pyroxene. ROSE. 



