PROFESSOR HEDDLE ON THE RHOMBOHEDRAL CARBONATES. 501 
which was still more siliceous than the dark foliaceous and cleavable granules. 
The specific gravity of the cleavable portions was 2:89; their cleavage angle, 
104° 45’. 
25 grains, not absolutely free from adhering paler cement, yielded— 
Silica, : ; : : é . 19°24 
Alumina, : 4 ; : ‘ "236 
Carbon, . ; : F ; ‘ 92 
Carbonate of lime, : : ‘ . 71:44 89°39 
A of magnesia, . , ; pe ail} 6°396 
a5 of iron, 5 . : . 1744 2°182 
fp of manganese, . 5 m9 . 1:624 2:032 


100°316 100-000 
Anthraconite.—From the north-west side of Loch Earn, Perthshire. The 
specimen was also given me by Dr MacponaLp. Occurs as a vein in clayslate 
in large foliated imbedded crystals ; colour, grey black, with granular cement 
of the same colour. Specific gravity of general mass, 2°759; cleavage angle, 
104° 58’, 
29°6 grains yielded— 

Insoluble, . ‘ : : . ¢ ; 12°205 
Carbon, : : ; : A : 7 016 
Carbonate of lime, . c : : : ‘ 86°741 
ie ofiron, . ; : : : : . 598 
99°55 
Other specimens equally dark in colour yielded no carbon whatever. 
The large quantity of foreign matter reduces the cleavage angle of these 
anthraconites. 
VOL, XXVII. PART IV. OR 
