FELSPAR.
As in the case of quartz, I shall here only notice the most remarkable and most rare varieties of this mine ral. I may remark, generally, that they are princi pally found in those districts which consist of gneiss, and are almost always integrant portions of the granite veins with which that rock abounds.
Pure White. Opaque. At Hillswick, in Shetland, intermixed with actinolite, and very splendent. At Cape Wrath, in granite veins. In Coll, Harris, and in Arisaik.
Trhite. Translucent where thin; splendent and re flecting much pearly light from the interior. This very beautiful variety occurs in Harris, on the south ern side of Roneval. The ordinary white varieties, under many different aspects, are too common to re quire particular notice.
TI bite. Crystallized. In Cairn Lia, one of the summits of Ben-y-gloe, in micaceous schist. In Aber deenshire, not very uncommon; particularly in the granite of Bennachie.
A brownish flesh-coloured variety, characterized by a high degree of transparency, and pearly lustre in the thin fragments, occurs in east Rona. A very beautiful yellowish flesh-coloured and
similarly splendent variety abounds in North Rona. This colour is here distinguished for its peculiar pu rity and beauty, compared to the ordinary colours of felspar.
This variety also abounds in North Rona, hut I have never observed it elsewhere.
Very bright. This occurs in Lewis, in Ardgower, and in Shetland, but is rare. Reds declin ing from this in brightness and purity, are too mon to require notice.
In Eriska and Fudia, and less per fect in Coll.
Inclining to purple in some in stances, and resembling that of a Labrador, but not iridescent. In Sky, in veins in hypersthene rock, and in Rum. In Aberdeenshire.
Glassy Felspar. In the basalts and clay-stones of the western islands in general. Very large in the clay stones of Blaven in Sky.