ay SY 
Atomic Volume of some Minerals. 235 
2, Spodumene. 
==6927 sid 6. atoms of acid and bases, 19. ¢. atoms of elements, 74. 
10196°838—3:17=3216-7 
ee Li 408- a B. 3216-7-19=169°3 C. 8216°7+74==43'47 
z Na 293°18 
a, At. weight, 10196-83 
Petalite has the structure of a feldspar, although not conform- 
ing to the general rule for the fe eldspar family in having the oxy- 
gen J the peroxyds to that of the protoxyds as 3: 1, but instead 
as 4: It also approaches Orthoclase in its atomic volume, B 
aealling 224-9 and C 57°31, while in Orthoclase B=231-3 and 
=60°4. Spodumene, on the contrary, although a lithia species 
like petalite, and having also the above ratio 4: 1, differs in its 
cleavage and in: its crystalline form, and is also widely removed 
from the feldspars in its atomic volume. 
~ 
to 
“ 
3. Andalusite, 
28i 1154-62 6. atoms of acid and base,5. ¢. atoms of elements, 23. 
3Al 1925-40 A. 3080:02-+-3°2 (sp. gr.) =962'5 
a. At. volume, 308002 B. 962°5-5==192°5 C. 962°5--23==11°85 
Andalusite has therefore the atomic volume of Spodumene, for 
C equals 41:85, while in the above it equals 43°47. Moreover 
the angle of the rhombic prism is nearly the same, it being in 
Andalusite 91° 33’, in Spodumene 93°. We may hence con- 
clude that the crystallization of Spodumene is not oblique like 
the Feldspars and Petalite (although often so ok re 
trimetric like Andalusite, and that the two species are isomorp 
XIX, Analcime, 341 Si2+Nas Si2+6H,—Sodalite, Na aoe Sisal re 
Haiiyne 20a 8+Na3 $i+341 Si,—Nosean Na 8+Nas Si+34 
These species are introduced here for comparison with Leucite. They seem to 
show that the monometric form in these silicates is connected with a high atomic 
Volume, the amount exceeding that of the monoclinic as well as triclinic feldspars. 
1. Analcime. 
8 Si wit hy 8. atoms of bases and acid, 20. ¢. atoms of elements, 65. 
SAL 1925 A. 8391-46+2°068 (sp. bowel 
8 Na nt B. 4057°7-+20=202'88 C. 4057°7-+65-=62'48 
6H 
a. At. weight, 8391-46 
2. Sodalite, 
48i 9309-24 4, atomsof bases and acid, 11. ¢, atoms of elements, 39. 
A. 6141°54-+2-29 (sp. gr. of Vesuvian var.) ==2682 
8 Al 1925-4 
8Na 11727 B, 2682-11244 0, 2682—-39==68'77 
1 Na 
"9 
1c 4433 Sp.gr. of Greenland Sodalite, 237. Thence C==66°45. 
a. At. weight, 6141-54 
