
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 253 
The labradorite of this locality does not seem, as is generally the case in 
these plutonic rocks, to have separated out first, but it is proportionally in such 
small amount as to make it difficult to determine this. Among the granules 
there are rarely elongated crystals ; these are not striated, though sometimes 
twins. It was colourless, or with a faint tinge of green, and had a vitreous or 
greasy lustre. Neither cleavage angle nor specific gravity could be taken. 
On 1°315 grm. On 1°621 grm. Average. 
Silica, - , 49-387 48 - 922 49-155 
Alumina, ‘ 29 -616 29 + 624 29 « 62 
Ferric Oxide, . 1°154 Eo 3 1*152 
Magnesia, : noo * 932 “911 
Lime, 4 lost td ° 309 15 +309 
Potash, ; ea *695 *695 
Soda, , Stas 2°914 2°914 
Water, AY 719 * 741 cies 
100 : 288 100 + 386 
Insoluble silica, 2-11 per cent.; probable impurity, a trace of augite. In the 
lime and alkalies this approaches anorthite, of which there was possibly an 
admixture. | | 
3. From near the Head of Loch Scavaig. 
This specimen, given me by Mr Grieve, was veryunlike the previous one. 
It consisted. of a large imbedded crystal, an inch and a half in length; it was 
associated with large greenish-brown, slightly bronzy-lustred crystals of augite, 
these being penetrated by small crystals of magnetite. The crystal of labra- 
dorite was of a bluish-grey colour, feebly lustrous, and indistinctly but finely 
Striated. 
The cleavage angle was 86° 42’; the specific gravity, 2°715. 
1-64 grammes gave— 
Siicaye. My os : F ; 50° 811 
Alumina, . : E ? 29°48 
Ferric Oxide, oo : * 252 
Magnesia, . ‘ : : °124 - 
Lime, . ; : : : 12°69 
Potash, . gy ee ‘ # 552, 
Soda,. : ; i : 3 °922 
Water, ; : : : a ‘481 
100 * 292 
‘VOL. XXVIII. PART I. 3U 
