This mineral occurs most frequently in the condition of amethystine quartz, in hexahedral prisms, lining the interior of geodes, in the bed of the River Desmoines, and on the Rock Rapids, in the channel of the Mississippi. The crystals which I have examined are generally limpid, with a high lustre, and of a pale violet color. Sometimes the tinge of color approaches to a full red, or is only apparent in the summit of the crystal. These geodes are sometimes eight or ten inches in diameter, with a rough and dark-colored exterior, often so nearly spherical as to resemble cannon _balls_. Some of the finest specimens I have observed from this locality are preserved in the museum of Gov. Clarke, at St. Louis, Missouri. Subs. 3.--_Ferruginous Quartz._ In amorphous masses, of a deep-red, brown, or yellowish-red color, along the southern shore of Lake Superior. Likewise, crystallized, in very minute hexagonal prisms, terminated by six-sided pyramids, of a reddish color, on the summit and declivities of the Grange de Terre. Subs. 4.--_Prase._ In the drift of Lake Superior. Its color is a light green and not fully translucent. It possesses a hardness and a lustre intermediate between waxy and resinous. Subs. 5.--_Chalcedony._ 1. _Common Chalcedony._--In globular or reniform masses imbedded in trap-rock, on the Peninsula of Keweena, Lake Superior. It is found sometimes in association with other quartz minerals. Its color is white or gray, sometimes veined or spotted with red. Also, constituting the interior lining of geodes at the rapids of Rock Island and the River Desmoines. These geodes, on breaking, often present a mammillary surface. In the form of translucent fragments, with a highly conchoidal fracture, among the debris of the shores of Lake Pepin. These fragments possess an extremely delicate texture, color, and lustre. 2. _Cacholong._--Some loose fragments of this mineral exist along the west shore of Lake Michigan, between Green Bay and Chicago. These fragments possess small cavities studded over with very minute and perfect crystals of quartz. 3. _Carnelian._--This mineral occurs in fragments in the debris of Lake Superior; also, in the amygdaloid; also, around the shores of the Upper Mississippi. Its color is various shades of red, or yellowish red, sometimes spotted or clouded, fully translucent, and occasionally presenting a considerable richness and beauty. Most commonly, the fragments are too small to be applied to the purposes of jewelry. Sometimes it is seen in very regular spheroidal masses, which contain a nucleus of radiated quartz. Some of the specimens would be considered as sardonyx.