452 S&S. L. Penfield—Tiemannite and Metacinnabarite. 
nation edge with the cube. The faces gave no reflection but 
were measured by covering them with glass plates and then 
measuring on the cube. This was repeated twice giving 
24° 49’, 25° 21’, calculated 25° 14’. 
n appearance the crystals resemble very closely those of 
sphalerite while the forms which are common to both are 
a(100, 7-2), o(111, +1), o(111, —1), w(611, +5-5) and m@1l, 
+3-3). 
2. METACINNABARITE. 
me, ‘T'wins parallel to an octahedral plane are very commo?, 
often repeated as in sphalerite, 
* This Journal, III, iti, 36. 
