PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 65 
sahlite), which occurs in the Glenelg limestone, and also thin veins which cut 
the serpentine of Portsoy (set down as being precious serpentine), I shall, after 
analysing these, take this question up in treating of the serpentines. 
RIPIDOLITE. 
From Limestone in Mica Slate. 
1. It is probably the continuation of the great bed of limestone which 
courses down Glen Tilt which crosses the Garry to the south of the village of 
Blair Athol, and which then curves westward by the Allt Bhaic. 
A small quarry of this limestone has been wrought on the south side of the 
stream, under the slopes of the Hill of Tulloch. 
The highly plicated beds of the lime contain scaly masses and rosette 
erystallisations of ripidolite associated with Biotite and quartz. The ripidolite 
is pale olive green in colour, and has a pearly lustre. 
The rosettes have a hexagonal arrangement, but the structure is not suffi- 
ciently simple and evident to allow of the form being determined. 
1°34 grammes yielded— 
Silica, ; : * 383 
From Alumina, . *023 
*406 = 30 * 298 
Alumina, . ; : xe Le OOT 
Ferrous Oxide, . : 7° 8 °232 
Manganous Oxide, . : 373 
Magnesia, . ‘ = 29 104: 
Water, . ‘ , ~ 13207 
100-474 
Insoluble silica, 6: 182 per cent. 
A perfectly similar mineral occurs in a limestone quarry north-east of 
Edintian ; this lime is probably the continuation of the Lude bed. The asso- 
ciates here are pyrrhotine, Biotite, sphene, and ilmenite. 
From Chlorite Slate. 
2. The southern half of the promontory of Hillswickness in the mainland of 
Shetland is composed of rocks which may be grouped under the above name. 
