Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820 / Resumed and Completed, by the Discovery of its Origin in Itasca Lake, in 1832

by Henry Rowe Schoolcraft

4. Septaria. In the reddish clay soil, between Montreal River and Lapointe, Lake Superior.

5. Gypsum. In the sandstone rock at the Point of Grand Sable West, Lake Superior. In orbicular masses, firmly imbedded. Not abundant. Granular, also imperfectly foliated.

6. Carbonate of magnesia. Serpentine rock, at Presque Isle, Lake Superior. Compact.

7. Hydrate of magnesia? With the preceding.

CLASS II. Earthy compounds, amorphous or crystalline.

8. Common quartz. Huron Islands, Lake Superior; also the adjoining coast. In very large veins or beds. White, opaque.

9. Granular quartz. Falls of Peckagama, Upper Mississippi. In sitû.

10. Smoky quartz. In the trap-rock, Keweena Point, Lake Superior, crystallized. In connection with amethystine quartz.

11. Amethyst. With the preceding. Also, at the Pic Bay, and at Gargontwa, north shore of Lake Superior, in the trap-rock, in perfect crystals, of various intensity of color.

12. Chalcedony. Keweena Point, Lake Superior. In globular or orbicular masses, in amygdaloid rock. Often, in detached masses along the shores.