150 schaller: crystallized variscite 



The material, when examined under the microscope, was seen 

 to be well crystallized in minute, colorless or pale yellow plates. 

 Some of these are square or oblong, others are irregularly shaped. 

 The rectangular plates give parallel extinction, with the axial plane 

 parallel to one of the sides. The axial angle is very large. The 

 thicker pieces are very slightly pleochroic in shades of yellow. 

 The double refraction is not very high. A few tabular pieces 

 showed an acute termination, the sides of which are inclined 52° 

 to the trace of the axial plane. Sections tabular parallel to a { 1 00} 

 show c{001}, m{011}, both large, and 6{010}, small. 



MINERALOGY. — Crystallized variscite from Utah. Waldemar 

 T. Schaller. To appear in a bulletin, " Mineralogical 

 Notes, Series II." of the Geological Survey. 



A sample of crystallized variscite from Lucin, Utah, collected 

 by Mr. D. B. Sterrett, furnished material for a determination of 

 the chief properties of the mineral. The bright green tabular 

 crystals are orthorhombic and in form similar to those of the anal- 

 ogous minerals scorodite and strengite, and of phosphosiderite, 

 which is held to be identical with strengite. Three different 

 orientations are possible for the variscite crystals and these are 

 described and their availability discussed. The optical relation 

 of barrandite to strengite and variscite is also considered. 



Some of the variscite crystals have included regular groupings 

 of small, variously oriented and irregularly shaped particles of 

 the same mineral. The green crystals are only slightly pleochroic 

 but on being heated before the blowpipe or up to 160° C, when 

 all the water is given off, the mineral becomes deep lavender with 

 strong pleochroism from violet to lavender. The mean refrac- 

 tive index (1.560) and the birefringence (0.032) of the green 

 crystals drop to 1.448 and 0.003 respectively, after heating. The 

 dehydrated, lavender-colored material is now, unlike the original 

 green-colored mineral, readily soluble in acids. 



The chemical analysis shows that small quantities of chromium, 

 vanadium, and iron are present but no adequate explanation of 



