848 APPENDIX. 



oidal, reniform, or globular. These agates are chiefly arranged 

 in concentric layers, which are white, red, yellow, &c., according 

 to the colors of the different varieties of chalcedonies, carnelians, 

 ifcc, of which they are composed. A close inspection would also 

 separate them into several varieties — as onyx, agate, dotted agate, 

 &c. 



Subs. 6. — Uornstone. 



In nodular or angular masses, imbedded in the secondarv lime- 

 stone of the west shores of Green Bay; and in the beds of argil- 

 laceous white clay strata of Cape Girardeau, of Missouri. Also, 

 on the hills of White Eiver, Arkansas. 



Subs. 7. — Jasper. 



1. Common Jasper. — In detached fragments, yellow, in the drift 

 of Lake Superior. 



2. Striped Jasper. — "With the preceding. Most commonly, these 

 specimens consist of alternate bauds of red and black, or brown. 



3. Red Jasper. — In quartz rock, Sagar Island, River St. Mary's, 

 Michigan. Masses of this mineral have been met in situ. 



Subs. 8. — Heliotrope. 



A fine specimen of this mineral, now before me, was procured 

 at the mouth of the Columbia River, Oregon. It is in the form 

 of an Indian dart. Its color is a deep uniform green, variegated 

 with small spots of red; those parts which are green being fully 

 translucent, the others less so, or nearly opaque. This beautiful 

 mineral is represented to have been in common use by the Indian 

 tribes of the Northwest Coast, for pointing their arrows, previous 

 to the introduction of iron among them. It differs chiefly from 

 the dotted jaspers of Lake Michigan, in its translucence and green 

 color. 



Subs. 9.— Opal. 



Common opal occurs as a constituent of agate, along with 

 chalcedony rarely, in the drift on the south shore of Lake 

 Superior. 



2. SiLicious Slate. 



1. Common. — In subordinate beds, in the argillite of the River 

 St. Louis, northwest of Lake Superior. 



