ON THE CONSTITUTION OF THE GRANITES OF DONEGAL. 67 
Brown’s Hill*, Barnesmore Mountains; Slieve League; Barnesbeg Gap ; 
Knockastoller. 
- Cuatcepony. In rolled pieces at St. Peter’s Lough, Mountcharles; in 
amygdaloidal trap at Doorin Rock* ; Cloghan (Greg and Lettsom); Ards. 
Very abundant in micaceous conglomerate in the baronies of Raphoe and 
Innishowen. 
Orat. At Mountcharles. 
Smiicrous Sanp. In great abundance, and extremely pure, on top of 
Muckish Mountain. 
Lypran Sronz. Common in the Carboniferous Limestone between Donegal 
and Ballyshannon. 
Anuyprovs SILIcaTEs. 
ANDALUSITE SECTION. 
AnpatusitE. In mica-slate, at Clooney Lough*, near Narin; on Scalp 
Mountain, four miles W.N.W. of Muff (Greg and Lettsom); at Barnesbeg 
Gap. 
rescue, Barnesbeg Gap. 
Kyanire. In mica-slate, with garnets, schorl, and sphene, in the reef of 
rock which runs from Fin M‘Coul’s Pan, Ballykillowen*, to Lough Derg; at 
Altnapaste ; near Doocharry Bridge. 
Frsrorire. In gneiss, in several localities, where that rock occurs in the 
granite, Croaghnamaddy*, near Dunglow; Lough Anure*, at the north end; 
Annagary Hill*, behind the pound. The best crystals are at Lough Anure. 
Beryt. In quartz veins and in granite, at Sheskinarone*, one mile north 
of Dunglow, on the road to Annagary. 
- Beryl occurs also, disseminated through the granite, at the same locality, 
in a subcrystalline condition, forming beryl granite. 
Tovrmattine. Schorl is very abundant in the gneiss in the neighbourhood 
of Ballyshanon and Donegal, especially about Ballintra*, and at Knader; 
with garnets and kyanite at Ballykillowen* and Golard*, near Donegal; in 
garnet-rock at Aghadoey*; in granite at Annagary*; at Cloghan; at Kil- 
madoo, parish of Clondehorkey; and at Glinsk, in Fanad. 
Indicolite—Some dark-coloured prismatic crystals, from the county of 
Donegal, occurring in granite, and labelled augite, proved on examination by 
Dr. Aquila Smith to be indicolite. 
Senuenn. Very abundant in granite throughout the county, especially in 
the white granite of Narin*, and Aphort*, Arranmore. 
In gneiss, with kyanite, schorl, and garnets, at Ballykillowen*. 
In a peculiar rock, consisting of orthoclase, green pyroxene, and quartz 
(sphene rock), which occurs in contact with the highly crystalline limestone 
of the granitic district of the country. 
It is most abundant at Annagary*, where there are two types of sphene 
rock—one containing small crystals of sphene, with dark green prisms of 
pyroxene, the other containing sphene in larger crystals, and in much greater 
abundance, and in it the pyroxene is of a light green colour and less distinctly 
crystallized. Also at Barnesbeg* Gap, near Kilmacrenan, where large nests 
of sphene are found; in Glenleheen*; and in the neighbourhood of Lough 
Nambradden*, near Fintown; at Cloghercor, parish of Innishkeel; and at 
Tirlyn, near Creeshlagh. j 
AUGITE SECTION. 
Pyroxenr. Two varieties, coloured light and dark green, occur with or- 
thoclase and quartz, forming sphene rock, at most of the localities where 
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