ANALYTICAL CHEMISTRY
1930 Space Group. C: - El. Formula Weights per Cell. 2. Formula Weight. 270.2. Density. 1.430 (flotation), I 43 from x-ray (lata Principal 1,ines I/Ii
d
:/I!
d
3.24 3.14 3.08 3.02 2.82 2.72 2.62 2.55 2.50 2.43 2.36 2.28
22 8
8 53 7.31 6.27 5.73 4.64 4.24 4.07 3.87 3.65 3.55 3.40 3.31
19
43 100 8 39 59 6 0 7 7
i
11
4 10
"1 l i
4 5
10
6 i
I/:,
d
2.21 2,00 2.04 2 00 1.937 1.906 1.878 1.819 1.823 1.794 1.715
OPTICALPROPERTIES
Refractive Indices (5893 -?.: 28" '2,). CY = 1.500 =t 0.001. 1.503 =k 0.001. i3 = 1.507 f 0.001. -1 = 1.042 3z 0.001. 1.631 + 0.001. Optic Axial Angles (5893 A: 28' C,). 21.: = 41 O, 2V = 27" thy stage goniometer). 211 = 27' (calcti. from B :tnd 2Ej. 2T7 2 (62 - a?) = 27'20' calcd. from sin2 1- = A2 (-. 2 - Nz)' -. Dispersion. Inclined, weak. Optic Axial Plane. 010. Optical Character. Positive. Acute Bisectrix. y A c = 14"40'. Extinction. Views showing parallel extinction with either y' or a' crosswise are most common, but occasional crystals growing on or nearly on 010 (Figure 2) Kill be found showing ohlique extinction with a making an angle of about, 8" with a. Molecular Refract,ion (5893 :\.: 38" C.1. Rcaiud = 62.1, Robad = 59.6. FUSION DATA.The melting point is approsimately 310": nith decomposition. Too much decomposition accompanies melting to make any sublimate or crystals from the brown colored mrlt useful in
