J. D. Dana on the characters distinguishing Kinds of Rocks. 341 
The following are analyses of the three prominent kinds, and 
of normal anorthite, labradorite and oligoclase. 
ne Se 
E SiO, #10, FeO; FeO MgO CaO Na,O K,O ign. 
1. L. Geneva _..____ 43°59 27°72 2°61 -—— 2°98 19°71 3°08 -—— 0°35=100-04, Hunt. 
4, i. Geneva. 2... 45°34 30°28 —— 1:37 3°88 13°87 4:23 —— 0-71= 99°68, Fikenscher. 
3. Schwartzwald _... 42°64 31-00 —— 2-40 5°73 821 3°83 3:83= 97-64, Hiitlin. 
Il. 
4. Mt. Genévre _____ 49°73 29°65 —— 0°85 0°56 11°18 4:04 0°24 3-75=100-00, Delesse. 
Dy CNG a oa 50°84 26°00 2°73 —— 0°22 14:95 4°68 0°61 1:21=101-24, v. Rath. 
a 51°76 26°82 1°77 —— 0°35 12-96 4°61 0°62 0°68= 99°57, Chandler. 
4 aA 52°21 29-64 0°48 —— 0-26 12°43 4-00 0°44 O-ll= 99°56, Heddle 
Rit oe 53°14 29°99 0°25 —— 0°21 12°29 3-86 0:47 0°21=100-42, Heddle. 
9. Durance... 2... 56°12 17°40 7°79 —— 3-41 8-74 3°72 0°24 1:93= 99°35, Delesse. 
Ill. 
10. Jadeite, China... 59°17 22°58 —— 1°15 1:15 2°68 12°93 fr. ——=100°07, Damour. 
2 Sat - 58°89 22-40 —— 1-28 1:28 3°12 12°86 0-49 0°20—100-63, Fellenberg. 
at “2... 68°28 21°86 —— 2°41 1°99 2°53 13°97 —— -— MnO 0-22, Fellenb. 
13. Normal an ies. 43:1: 865 2 — 200 — — —=+100 
14, Normal labradorite 52°9 30°3  -—— ——- —— 123 45 -— —=$—100 
15. Normal oligoclase. 61°9 24-1 ——- —- —— 52 88 -—— —-=100 
Specific gravity of 1, 3-227; of 2, 3-3-3°4; of 3, 3°16; of 4, 3:10; of 5, 2998; 
of 6, 2°74; of 7, 295; o ; 
the specific gravity of labradorite and was therefore that species, a mineral that 
would be present where the crystallization took p without, or with only par- 
tially, the conditions needed to produce saussurite. No. 9 is of the globules of 
the “ Variolite of Durance,” a rock associated with euphotide. ve 
Boulanger’s saussurite, from Corsica, is near zoisite in composition and density 
(G.=3-18), as stated by T. S. Hunt, who referred all true saussurite to zoisite (con- 
ing his view by his analysis above), and the part near labradorite to that of 
feldspar. Damour obtained for jadeite the ratio 1: 2: 6. 
. - 
differences, makes it desirable to distinguish such rocks by : 
Special name, The saussurite, and not the foliated mineral, is 
the chief ingredient on which the distinction rests. ner 
Euphotide is therefore a different rock from any consisting 
of cleavable labradorite and pyroxene or hornblende, both ‘on 
mineralogical and geological grounds. The foliated condition 
of the latter constituent is not reason enough for overlooking 
