456 PROFESSOR HEDDLE ON 
4. Occurs in imbedded patches, and rarely in dodecahedral crystals, in the 
granitic belts of the gneiss, on the cliffy shore opposite to the island of Koil- 
skeer, in the north of Sutherland. The colour is somewhat of a brownish- 
black, the lustre rather dull. 
It yielded— 
Ferric Oxide, : : ; : ; 89 * 632 
Ferrous Oxide (Fe. 3:208 —3°389), av. 4°241 
Manganous Oxide, . : - : 3 
Lime, : : : : : ; 2° 688 
Magnesia, . : : : . : a) 
Silica, : ; , 3 : ; 1:9 
Titanic Acid, : : : F : 45) 
100 +161 
There is here a marked passage into martite; but the specimen analysed 
was taken from a stone in a wall, and may have suffered from long exposure. 
5. Was taken from the great granite veins in the east foot of Roneval, 
Harris. It is found, along with Haughtonite, in imbedded plates, which are 
rough flattened octahedrons. 
These are sometimes an inch or more in size. 
Their colour is blue-black; the colour of the powder is the same. S. G. 5°154. 
It yielded on 1+ gramme— 
Ferric Oxide, ' : : ; : 68: 095 
Ferrous Oxide, . : ; : ; 29: 014 
Manganous Oxide, : ™5 
Alumina, . : : : ; : -615 
Lime, . A ‘ : 3 , : 168 
Magnesia, . : ; :; : : 6 
Silica, ; , ; 5 : : is 
100 «002 
There was possibly a slight admixture of Haughtonite, but none was visible. 
Chromiferous Magnetites. 
I have stated above that I found several of the “ magnetic iron sands” to 
contain traces of chromium. 
Where these sands may have been extracted from a serpentinic rock, or 
from diorite, this may fairly enough be assigned to a small admixture of 
chromite. Dr. WoLuasTon states that the metallic specks which occur in the 
