PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 19 
Loss in bath -454 per cent. 
The amount of iron only was determined in the dark brown plates; these 
contained of ferric oxide 4913, and of ferrous oxide 19°802 per cent., this 
large amount replacing lime and magnesia. 
The large amount of lime in the pale variety is singular, taken in connection 
with the small amount of that earth contained in the Biotite found in limestone 
from a near-adjacent quarry. (See analysis No. 1.) 
Biotite. 
Sei) sl ae Woe, |) Fem! te, | ea | ae. | ky | way | a | By, Total. 
Glen Urquhart, . | 2867 || 38°69| 17-66] -25 |12°95| ... | 146 |17-54| 8-92] as] s2| 214|| 99-96 
Laggan, . .| ... |(39°5 |15-04| -24|10-23) -75| 1-4 [18-46] 9-37] -62| -73| 3-21 || 99°55 
Shinness, . .| ... ||39°77|16-68| -65| 6-73| -62| 22 |20-:92| 65 | -48| ... | 5-4 || 99-95 
Glen Beg, . . [2°85 |[39-46|16-45| 39 |10° | -53| 1:59 [19 | 822] -26| -32| 3°34 || 99-56 
Hillswick, . .| .. ||39°8 |14-19| 2°59 J 11-58] -24| -1 | 18-32] 8-43 | 2-11| -56| 2-52 || 100-44 
Milltown, Urquhart| 2-781 |) 40-31 | 12°58] 1-81 | 3-35| -38| 7-58 |a1- | 6-56| -95) ... | 5:74 || 100-25 
| 
The latest published analyses of Biotite show that the iron is almost totally 
in the state of protoxide, and the above analyses put the matter beyond doubt. 
The above Biotites were optically uniaxial, or biaxial to a very small 
extent—1° to 2°. 
LEPIDOMELANE. 
From Gneiss. 
1. This mica—which Haughton has the credit of first introducing as British, 
if not of firmly establishing as a species—I have only found in Scotland at two 
localities. The first is near the north shore of Loch Shin, in Sutherland. 
Not a little of the gneiss of central Sutherland is, in this neighbourhood, horn- 
blendic. A bed of hornblendic rock occurs immediately over the limestone of 
Shinness, like it, with a northerly dip ; to the north, and superior to this, again, 
a hornblendic gneiss stretches west and east for several miles. 
The country is for the most part covered, but the rock has been exposed 
here and again in the drain cuttings made in connection with the great 
improvements at present being undertaken by His Grace the Duke of 
Sutherland. 
