16 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
CALCITE. 
Calcite was noted only once as a snow-white nodule in a cavity in 
rather dense basalt from the Spokane River at Wall Street. The 
snow-white nodule rested lightly on several chain aggregates of 
second-generation siderite. The interior structure of the nodule 
was radial-fibrous, and it was very friable, the fibers separating 
readily. It was readily soluble in cold dilute acid. Measurement 
of the indices of refraction showed that this carbonate was calcite 
rather than aragonite. While the exterior of the nodule bristled 
with minute terminations, these were etched dull and no measure- 
ments could be made. 
BARITE. 
Barite occurs in only one specimen, where it is abundant as a 
crust of acicular colorless crystals up to 2 mm. in length. It is 
associated with both second-generation siderite and hyalite, and 
although it is later than both of these it has deposited between 
them on the lining of the cavity in preference to resting on either. 
Under a lens the barite resembles quartz to a remarkable degree. 
Under the microscope crystals resting on a tabular face of c (001) 
show the emergence of the obtuse bisectrix, and well-defined cleav- 
age parallel to m (110). The orientation adopted in the drawings 
gives optical orientation in agreement with the data given for 
barite, while one index on such a section is higher and one is lower 
than 1.640. The resemblance to quartz crystals is heightened by 
tapering of the crystals, this distortion amounting to 10° or more, 
as shown in the drawing, figure 13. The most highly modified crys- 
tal seen had the development shown in figure 14. The smaller faces 
are very minute and give very faint signals, while the distortion 
mentioned affects the angles. The measurements obtained on the 
crystal (fig. 14), are given below: 
Forms and angles of barite crystal from Spokane. 
| Measured. Calculated. 
Letter. | Miller. Reflection, etc. 
? p r p 
Czcacely OGL O iViemproods tq 6a ctu. Sees itapae 0 00 ghee 0 00 
Use 010 | Bright narrow line........../ 0 07| 90 00; 0 00; 90 00 
mi 2i/[9 TIO iVeryigood? 205.02. 98. . 50 49] 90 00; 50 49 90 00 
N----- 320 | Very minute, no signal. ....- 59 06| 90 00}; 61 28 90 00 
Nese 2107 Small but, brenG. . o5 <1-mi 68 29] 90 00) 67 49 90 00 
OROTEL 011 | Blurred, distorted....-....--.- 5 00} 52 40 0 00 52 43 
Us Ns 101 | Very faint, minute..........-. 88 08 | 61 26}; 90 00 58 10 
ce eee 102.) “Veryr pode eco. 5 50 ter 5 ok sos So sou, 39 OL | 90° 00 38 51 
Wei8.|' 21108.) Poor rotinded . SL. Le 88 16} 12 51}; 90 00 ll 23 
Cree lig lelel AW) (GOO Ske ik Sycaee hy aia ee |. 50) 62 64 20 50 49 64 18 
Uietaeer 1220) MuIMube tant ere secs errs 28 54} 56 44) 31 31 57 O01 
pres 144 | Very poor, minute, rounded..| 17 13 | 53 39) 17 08 53 57 
K..=.| 223 |) Very poor, no signghen ccsecun 49 29| 53 08}; 50 49 54 11 
