A, J. Moses — New Mercury Minerals from Texas. 263 



5. An undetermined yelloio mercury mineral. 



The second specimen received from Prof. Penfield and one 

 received from Mr. W. P. Jenney show small yellow needles 

 and short prismatic crystals which suggest hexagonal prisms 

 and a basal cleavage. There w^as not sufficient material for 

 analysis but the closed tube test showed mercury and apparent 

 mercurous chloride suggesting an oxychloride, and the fact that 

 the color did not noticeably change on long exposure indicated 

 a different species from those described. An optical test made 

 by carefully rubbing a basal cleavage down to transparency 

 showed an indistinct biaxial brush in convergent light and 

 double refraction in parallel light. The symmetry is there- 

 fore not higher than that of an orthorhombic class. 



Two crystals were measured but the results were entirely 

 unsatisfactory, the apparent faces being irregular and frequently 

 yielding two reflections several degrees apart. The only sug- 

 gestion resulting from the measurements was a very acute 

 orthorhombic or monoclinic form, the faces making an angle 

 with the apparent basal cleavage of about 85^ degrees. Pend- 

 ing the obtaining of more material the substance can not be 

 described definitely. 



