268 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 

that the gravity of orthoclase must be regarded as a highly characteristic — 
physical feature. 
The specific gravities of the Albites determined are— 
Colafirth Voe, Shetland (av. of 4), 2 - 607 
Nudista, Hillswick (av. of 2), 2°615 
Beautiful Rock, Colafirth, 2-622 
Cleavlandite, Sutherland, 2-622 
Moonstone, Harris, 2° 627 
Average, 2°618; the range, ° 02. 
Of Oligoclase :— 
Anguston, 2°611 
Lairg, Sutherland, 2°618 
Craigiebuckler, Aberdeen, ; : ‘ 5 : .) 2.622 
Ben Dubh, Coyle, Aberdeen, ; : ; ‘ : od, OZ 
Rispond, Sutherland, 2° 636 
Rubislaw, Aberdeen, 2° 637 
Geo-na-Shermaig, Cape Wrath, 2° 654 
Barrahill, Aberdeen, . : 2* 834 
Average, 2°655; the Soaeue of the a Hill gives here the large” 
range :223. Excluding the anomalous Barra Hill specimen, the average is 
2° 629, and the range only ° 043. | 
Of Andesine— . 
Glen Urquhart, Inverness-shire, 2° 672 
Crathie, Aberdeenshire, 2° Oi 
Glen Gairn, white, Aberdeen, 2-689 
Cowhythe, Banffshire, 2° 692 
Glen Gairn, blue, 2°'705 
Average, 2687; range, * 033. 
Of Labradorite— 
Portsoy, massive, Banffshire, . 
Glen Bucket, Aberdeen, 
Kildrummy, Aberdeen, 
Badnagoach, Aberdeen, 
Balvraid, Glenelg, granular, 
Balvraid, Glenelg, fibrous, 
Loch Scavig, Skye, 
Portsoy, crystallised, 
Balta, blue, Shetland, 
Balta, white, . 
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Average, 2°755; range, °* 282. 

