70 
often occurs with perfect crystalline form, showing the 
prismatic and the orthopinacoidal faces. Its extinction 
is larger than is usual in brown hornblendes, reaching 20°. 
It possesses a strong pleochroism. The hornblende 
in a state of perfect purity was analysed by Professor 
Norton-Evans, of McGill University. The results of the 
analysis are given below, together with those of several 
hornblendes of similar composition which have been 
added for purposes of comparison: 
SiOs te. ies 38 -633 39°75 40°15 40°14) 41-35 39:16 
GB Oa ss 5035 5°40 5°21 4°26 4.°07\ 2 eee 
POs tees 11-974 15:00 14°34 14°30 13°4 14°39 
FeO3; 0.4.5 3-903 7:86 7-80 7-07 5:14 12-42 
HeO ees es 11-523 2-89 4°53 6-27 10-33 5°85 
Min@i;* 2c" 02720 |6 fo... ole eee O°21 hae eee 1-50 
1A Wed O essPecr sr 10-200 14-16 13°14 11-62 11-44 10°52 
CAOr i. tar 12-807 12-97 11-75 12-00] . 10-93 11-18. 
NaO). se 3°139 1-92 2:31 222 2-10 2-48 
| A ae enier 1-489 I-61 I-14 1°35 0-62 2-O1 
BLO ee OFS30 IS Foyer etter ne heats Cae 0-48 0-39 
99°762) 101-56} 100-37 99°44; 100-84) | 99-90: 
No. 1.—Hornblende. From the essexite of Mount Johnson, Pro- 
vince of Quebec, Canada. 
No. 2.—Hornblende. From Bohemian Mittelgebirge. 
No. 3.—Hornblende. From tuff of hornblende basalt, Hartlingen, 
Nassau. 
No. 4.—Hornblende. Basalt tuff, Hoheberg, near Giessen. 
No. 5.—Hornblende. From ‘hornblende diabase,’’ Graveneck, 
near Weilburg. 
No. 6.—Hornblende. Syntagmatite. Jan Mayen. 
The hornblende thus belongs to the class of basaltic 
hornblendes. 
Pyroxene occurs intimately associated and often 
intergrown with the hornblende, both minerals frequently 
holding many inclusions of magnetite and apatite. It is 
pale greenish in colour, with no perceptible pleochroism, 
but with a marked dispersion of the bisectrices. 
