The silicious feldspar, which I suspect to be the basis of the granite, crystallizes in thin rhomboidal tables. They are very frangible, and have one clivage perpendicular to the faces of the tables. Sometimes the tables have one lateral edge or more truncated. In one fragment of a crystal I observed a very obtuse acumination on the table, which appeared to be diedral, the sides being placed on the obtuse lateral edges of the tables. On account of the extreme frangibility of the crystals, it is certainly extremely difficult to seize their characters. Specific gravity only 2.333, probably owing to interstices between the tables. The colour is white, translucid, passing to semi-transparent; lustre sometimes dull, at others shining. The tables are sometimes so aggregated that their edges being exposed, offer wedge-shaped and stelliform figures. The tourmalines are chiefly contained in this vein. They are red, or green, rarely blue or black. The green tourmalines vary from one-eighth of an inch to one inch in diameter; they are sometimes four inches in length, and are entirely confined to the inner vein of quartz. They are triedral prisms, with convex faces, striated longitudinally, and generally traversed perpendicularly to the axis, with very small fissures filled by some silicious substance, probably feldspar. These green crystals are opaque. The red tourmaline is frequently enclosed in the green. In certain parts of the vein almost every green crystal encloses a red one, which always corresponds by its sides and angles with the exterior crystal. Sometimes a thin layer of talc intervenes between the outer and inner crystal. In one specimen I found three crystals of the red aggregated together, and enclosed in one of the green. In another crystal I found pyrites in the place of the red tourmaline. The largest crystal of the red was one quarter of an inch in diameter, and four inches long. The red tourmalines vary in intensity of colour, and frequently (particularly in the interior) pass into violet. They pass from translucid to semi-transparent. I have found some that were terminated by triedral pyramids. The crystals are generally perpendicular to the sides of the vein. Small crystals of the red often run from the vein of quartz into the adjoining feldspar. The granite also contains minute crystals of dark and light blue tourmaline, and pale green emerald, with a very few garnets and pyrites. In the lower part of the vein, five to six feet from its interruption by the mica slate, the red tourmaline scarcely appears, and the vein contains chiefly bluish amorphous quartz and green tourmaline. It is therefore probable that this vein will not afford henceforward a great supply of this beautiful mineral.