30 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
1°3 grammes yielded— 
Silica, ; 4 : -445 
From Alumina, . : °012 
a5, = ~So-iibe 
Alumina, . . ; - 16 704 
Ferric Oxide, . : . SSG 
Ferrous Oxide, . ; . 19063 
Manganous Oxide, . ». 2306 
Lime, : : 5 °818 
Magnesia, . . 7° 461 
Potash, . : y . 9°243 
Soda, 1°259 
Water, 8°133 
99-812 
Possible impurity unknown. 
From Eajiltration Veins in Syenitic Granite. 
10. From an exfiltration vein in the so-called syenitic granite of Cnoc-dubh, 
about a mile east of Lairg, Sutherland. 
The associated minerals in this vein are quartz, orthoclase, oligoclase, sphene, 
and Allanite. Colour dark green. Lustre greasy. No plate large enough and 
transparent enough to determine the optical properties could be got; nor 
could a portion large enough for determining the specific gravity be found. 
On ‘72 grammes— 
Silica, : f : *245 
From Alumina, . : Our 
256 = 35:°565 
Alumina, . ; ‘ . 16°694 
Ferric Oxide, . ‘ Lei: 883 
Ferrous Oxide, . : , ub 037, 
Manganous Oxide, . ; 694 
Lime, F , ; 2 2 722 
Magnesia, . 8'472 
Potash) = : , 9:896 
Soda, { ; : ; 105 
Water, 5° 714 
99-772 
Insoluble silica, 10°546 per cent. No fluorine; possible impurity, ortho- 
or oligoclase. Some lighter-green plates had a slight appearance of decom- 
position. 
