PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 511 
1-3 grammes yielded— 

Silica, . : é 7079 
From Alumina, . -006 
* 685 = 52° 692 
' Alumina, ; 2 af 556 
Ferric Oxide, . . . 4:°086 
Ferrous Oxide, . 9.772 
Manganous Oxide, . 23 
Lime, ‘ : : « D-A19 
Magnesia, : : oc VosiGg 
Potash, . : : ; B57 
Soda, 3 ; 2 : ° 693 
Water, : : ‘ 5 AO TANS 
99 - 912 
Insoluble silica, 1 - 897 per cent. ; loss in bath, - 242 per cent. ; there was a 
Suspicion of coloration from copper, but none was found. 
Octohedrite (Anatase) and chabasite have been said to occur here. The 
| mistaken for the first consisted of minute octohedral crystals of 
magnetite ; that taken for the second was rhombs of pale-brown dolomite ! 
The crystals of magnetite are imbedded in the hornblendic schist. 

| 
Magnesia, Iron, Lime Amphibole. 
FHornblende Proper. 
From Diallage Rocks. 
12. The diallage of Balta has been stated,—both in my chapter on the Felspars 
and in speaking of the Augites,—to contain, opposite the little Brough, two 
pseudo veins, of which the matrix is massive labradorite, but of which the one 
carries imbedded crystals of diallage, and the other of hornblende. It is this 
hornblende which is here described. It is in large dark-green, dull, somewhat 
foliated crystals ; these show thin rifts filled with calcite, possibly the result of 
incipient alteration. Specific gravity, 3°112; cleavage angle, 124° 27’. 
