Dec, 1908. Mineralogical Notes 159 



large and small calcite crystals. The color of the realgar in both 

 specimens is a superb carmine-red. The crystals are transparent. 

 The habit of the crystals in the specimen numbered M 8204 is, as is 

 usual with realgar, short-prismatic. These crystals are highly modi- 

 fied and doubly terminated. A marked feature is the large number 

 of prisms present, no less than nine being observed. The planes are 

 remarkably brilliant and afford excellent signals on the reflecting 

 goniometer. The prisms are often scarcely more than lines, but 

 nevertheless give well-defined signals with the goniometer. In some 

 of the crystals the basal plane is quite prominent, while in others 

 pyramids and clinodomes are extensively developed. The clinopina- 

 coid may also be quite fully developed. The two most prominent 

 types exhibited by these crystals are shown in Figs. 1 and 2, PI. 

 LIV. As there represented, a slight elongation in the direction of 

 the clino-axis usually occurs. The crystals average about 4 mm. in 

 length. 



The specimen numbered M 8205 is from the Golden Gate mine. 

 In habit the crystals of this specimen seem to be different from any 

 hitherto noted in realgar in that the prism is elongated in the direction 

 of the vertical axis. None of these crystals is doubly terminated. 

 The terminations on the single terminated end are simple as com- 

 pared with those of the crystals previously described and there is no 

 large number of prisms present. The prismatic development here is 

 produced chiefly by the prisms m (no) and / (210). Like the crystals 

 previously described these crystals also show a slight elongation in 

 the direction of the clino-axis. The average length in this direction 

 is about 7 millimeters. In the direction of the vertical axis a length 

 of 15 millimeters is frequently exhibited. Fig. 3, PL LIII, illustrates 

 these crystals. Some of the smaller crystals of this specimen are 

 hollow in the direction of their length. A basal projection of all the 

 forms observed upon both specimens is given in Fig. 4, PI. LIV. 



The following is a list of the forms observed, together with meas- 

 ured and calculated angles: 



r (012) w (430) e (In) 



y (032) 77 (650) n (2i2) 



x (Toi) m (no) 



