Occurs rarely in the granite of Lake Superior. It is found in place on the Huron Islands. Also, in minute folia, in the alluvial soil of the Upper Mississippi. A beautiful aggregate, consisting of plates of gold-yellow mica, connected with very black and shining crystals of schorl, has been dug up from the alluvial soil of the Island of Michilimackinac. 5. SCHORL. 1. _Common Schorl._--In crystals, in boulders of granite, at Green Bay. 2. _Tourmaline._--With the preceding. 6. FELDSPAR. As an ingredient in the granite of Huron Islands, Lake Superior. Also, in detached masses of granite along the west shores of Lake Michigan. Also, in the form of prismatic crystals of a light-green color, in the rolled masses of hornblende, porphyry, greenstone, and epidotic boulders of Lakes Huron, Michigan, and Superior. 7. PREHNITE. This mineral occurs at Keweena Point, on Lake Superior. It is found in connection with isolated blocks of amygdaloid, of primitive greenstone, and of petrosilex. Sometimes native copper, and carbonate of copper, are also present in the same specimen. In some instances, a partial decomposition has taken place, converting its green color into greenish-white, or perfect white, and rendering it so soft as to be cut with a knife. Sometimes the grains or masses of native copper are interspersed among the prehnite, and slender threads of this metal occasionally pass through the aggregated mass of greenstone, prehnite, &c., so that, on breaking it, the fragments are still held together by these metallic fibres. 8. HORNBLENDE. 1. _Common Hornblende._--Occurs as a constituent of the hornblende rocks near Point Chegoimegon, Lake Superior. Also, at the Peace Rock, on the Upper Mississippi, and in certain granite aggregates, and rolled masses of porphyries, &c., around the shores of Lakes Huron, Michigan, and Superior. 2. _Actynolite._--In slender, translucent, greenish crystals, pervading rolled masses of serpentine, on the west shores of Lake Michigan. 9. WOODSTONE. 1. _Mineralized Wood._--In bed of the River Des Plaines, Illinois. 2. _Agatized Wood._--This variety of fossil wood is found along the alluvial shores of the Mississippi and of the Missouri. c. _Calcareous Minerals._ 1. CARBONATE OF LIME. Of a substance so universally distributed throughout the western country, it will not be necessary to give many localities, and these will be principally confined to its crystalline forms. Subs. 1.--_Calcareous Spar._