Hillebrand and Washington — Minerals from Utah. 303 



4. Chalcophyixite. 



This mineral occurs in the form of small hexagonal plates 

 arranged in rosettes, differing from the radial arrangement of 

 the supposed tyrolite. It showed the same bright apple-green 

 color, pearly luster, and perfect basal cleavage. An optical 

 examination proved it to be uniaxial with negative double 

 refraction. 



These crystals showed several planes replacing the edges, and 

 measurements were made of them as far as possible. The 

 angles did not agree very closely owing to the imperfection of 

 2 all the surfaces, but they were suffi- 



ciently exact to prove the presence of 

 r (1011, R), <s(01I2, -%B\ and two other 

 rhombohedrons, new to the species, hav- 

 ing the symbols w (10i6, -\jR), and 

 <Z(01I3, -%B). The figure shows the 

 habit of the crystals, but with d absent, this plane being only 

 observed in one instance. The very rough angles obtained are 

 given below : 



Observed. Calculated. 



c^r, 0001 ^1011 ==11° 2V 11° W 



c^iv, 0001^1016=26° 10' 26° 10' 20" 



c~e, 0001^0112 = 56° 51' 55° 51' 10" 



c~d, 0001^0113=41° 50' . 44° 30' 30" 



The above observed angles are the means of several measure- 

 ments which vary among themselves from one to three degrees. 

 The fair agreement in the first two results therefore is merely 

 accidental, and no value can be attached to these measurements, 

 which are inserted because the measurements of this species are 

 extremely few. 



The mineral was not analyzed for want of sufficient material. 

 On heating, it decrepitated as violently as the last mentioned 

 mineral, and in the flame of the burner fused, though not with 

 the same readiness. 



5. Clinoclasite. 



The clinoclasite occurs in two distinct habits, one dis- 

 tinctly crystallized and the other in barrel shaped or globular 

 forms. It is of a dark bluish green color, almost black by re- 

 flected light, bright green by transmitted light. Streak and 

 powder bluish green. Specific gravity at 19° C, 4 - 3S. (1-36 

 Pearce.) Hardness 2 '5-3. 



At first sight these crystals seemed to be very promising and 

 likely to afford good fundamental measurements for the 

 species. But on further examination they did not come up to 

 our expectations, c(001, O) and s(302, f--*") being the only two 

 planes giving even fairly good measurements, in (110, /), 



