534 APPENDIX. 



3. A General Summary of the Localities of Minerals ohserved in the 

 Northwest in 1831 and 1832. By Henry E. Schoolcraft. 



CLASS I. Bodies not metallic, containing an acid. 



1. Calcareous spar. Keweena Point, Lake Superior. Im- 

 bedded in small globular masses, in the trap-rock ; also forming 

 veins in the same formation. Some of the masses break into 

 rhombic forms, and possess a certain but not perfect degree of 

 transparency ; others are opaque, or discolored by the green car- 

 bonate of copper. Also in the trap-rock between Fond du Lac 

 and Old Grand Portage, Lake Superior, in perfect, transparent 

 rhombs, exhibiting the property of double refraction. Also, at 

 the lead mines, in Iowa County, in the marly clay formation, often 

 exhibiting imperfect prisms, variously truncated. 



2. Calcareous tufa. Mouth of the Eiver BruM, of Lake 

 Superior. In small, friable, broken masses, in the diluvial soil. 

 Also, in the gorge below the Falls of St. Anthony. In detached, 

 vesicular masses, amidst debris. 



3. Compact carbonate of lime. In the calcareous cliffs of 

 horizontal formation, commencing at the Falls of St. Anthony. 

 Carboniferous. 



4. Septaria. In the reddish clay soil, between Montreal Eiver 

 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 Missis- 

 sippi. In situ. 



10. Smoky quartz. In the trap-rock, Keweena Point, Lake 

 Superior, crystallized. In connection with amethystine quartz. 



