346 APPENDIX. 



degree of translucence in some places. It exists in mass at Huron 

 Bay, Lake Superior, and in fragments of red jasper on Sugar 

 Island, St. Mary's Eiver. 



1. Radiated Quartz. — In detached masses on the Grange, and 

 also at the rapids of the Kiver Desmoines, on the Upper Missis- 

 sippi. At the Grange, the crystals, which are usually minute, 

 sometimes possess a cinnamon color, or pass into a variety of 

 crystallized ferruginous quartz. 



2. Tabular Quartz. — In small, flattened masses along the shores 

 of Lake Pepin. These masses are transparent, or only translu- 

 cent. Their color is generally white, but sometimes yellow.- 

 The}^ appear to be closely allied to chalcedony. 



3. Greasy Quartz. — In detached masses along the shores of 

 Lake Superior. 



4. Granular Quartz. — At the Falls of Puckaiguma, on the Upper 

 Mississippi, in large, compact beds rising through the soil. Also, 

 in some conditions of the cliffs commencing at the Falls of St. 

 Anthony, Carrer's Cave, &;c. 



5. Arenaceous Quartz. — This is sometimes the condition of fine, 

 even-grained, translucent sand rock of the preceding localities. 

 Valuable as an ingredient of glass. 



6. Pseudoviorplious Quartz. — On the shores of Lake Pepin, oc- 

 casionally. These masses appear to have taken their crystalline 

 imjifess from rhomboidal crystals of carbonate of lime. 



7. Amethystine Quartz. — In the trap-rock of Lake Superior, 



Subs. 2. — Amethyst. 



This mineral occurs most frequently in the coudition of ame- 

 thystine quartz, in hexahedral prisms, lining the interior of geodes, 

 in the bed of the Eiver Desmoines, and on the Eock Eapids, in 

 the channel of the Mississippi. The crystals which I have ex- 

 amined 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 halls. Some of the finest specimens I have ob- 

 served from this locality are preserved in the museum of Gov. 

 Clarke, at St, Louis, Missouri. 



