224 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
1°503 grammes yielded— 

Silica, F ; 5 2 "63" 073 
Alumina, . f ; . 18:°686 
Ferric Oxide, . : Sve ei eede 
Oxide of Manganese, ; *059 
Lime, F : : 3 GacAgs 
Potash, . : : », 6-689 
Soda, ; A ! Piedad £5 Yd 3) 15) 
Water, . : : J MILLERS SS 
99 - 996 
14 °557 per cent. of the silica insoluble ; possible impurity, the matrix. 
The structure of some of these crystals is of a very extraordinary nature, 
and will, in a future chapter, be described. 
In the somewhat less friable tuff of the Kincraig, near Elie, and of two 
dykes to the east of that town, a felspar identical in every way in appearance is 
found. 
Both 16 and 18 are sanidine. 






















ORTHOCLASE. 
Colour. | Cagis. | Gravity, || & | alg0. |e,0;| ain.| itg.| Ga. | ip | Nop | Hp || Te 
Ben Capval, . .| Blue 89 50 | 2:565 || 64:86/18-47| -67| ... | -71] ... | 12°98} 1:89] °5 || 100-09 
Stromay, Harris, .| Grey 89 55 2574 || 65°35) 17°68) °92] ... | 25) +68) 13°13 | 2°5 18 |} 100°69 
Glen Fernate, .| Pink 90 2°525 || 68°99 | 17:06 | 2°47] ... | 07 | °52] 14:85] 53] 65 || 100°17 
Cowhythe, 3d vein,} Flesh A 2°561 || 64°74/18°3 | 1°99] ... | 04] °97| 9°87| 3°34) °17 || 99°43 
Do. 4th vein, Do. 89 40 | 2°559 || 66°0 |18°3 | 2°03]... |]... | 1: | 10°02|)3:19] -16 || 100-71 
Clattering Briggs, .| Fawn 53 “igh 64°03 | 19°17] °3 | °22/°94|)1°4 |11°84)1:37| 57 || 99°83 
Rubislaw, . -| Flesh 89 58 | 2°554 || 64:54) 18°36] °32] ... | 09] .86] 13°05 | 2°58] -09|| 99°39 
Lairg, . 2 .| Butf 89 59 | 2°555 || 62°62/19°63) ‘06|.... | 64] °6 | 13°72) 2°92] +13 |} 100°32 
Tongue, A .| Green 89 43 | 2°569 || 64:2 | 18°39] °45) 15] 07) °72/12°75|2:95| -51 || 100°22 
Froster Hill, . .| White | 89 58 | 2°548 |/ 63°31 |18°17) °87]... | ... | 1°07 | 13°27] 2°06} :81}) 99°51 
Blirydrine, . .| White | 89 41 | 2-551 |] 63°59/19:58|1:09| ... | 08] ‘68 | 12°53 | 2°76) °42 || 100-73 
Banchory, . .| White | 90 2°554 || 63°11/18°98|] °98] ... | 57] 88] 18°06 | 2°34] °34 || 100°26 
Balvraid, . .| Blue 89 58 | 2°558 || 68°04|}19°31] ... | ... | 21] °97| 14°63 |1°02} 56 || 99°74 
Struay, Ross, || Wena uae 2°543 || 65" | 17°08 | 1-43 | “69 | ... | -°73 | 18°82 | 1° 50 || 100°20 
Do. Do. -| Blue 89 50 | 2°545 || 64°19|17°39 | 1-2 | -46/... | 69] 18°31/1°96| °56 || 99°76 
Canisp, Sutherland, } Brick ig 2°545 || 63°54 | 17°36 | 1°87 | °388} .... | 1°33 | 12°93 | 1°69 | 1°12 || 100°24 
Ratio of Soda to 
Potash # to 1; to 2 
to 1, Sanidines. 
Corriegills, .|Colourless|  ... ..  |'66°85|17:24] °42] ... | 06/ 1°22) 9:2 | 4:32] -86]| 100717 
Kinkell, : ae 89 50 | 2°609 || 63:07 | 18°69 | 2°47| -06| ... | 2°2 | 6°62/5°5 |1°39]} 99°99 



The peculiarity of structure, more than once noticed above, I shall now 
describe. I first observed it, many years ago, in the Rubislaw crystals; and 
now find it to be very generally, if not always, to be seen in the felspar of veins” 
or dykes, especially of exfiltration veins. 


i i ii hi i i is i 
