2he Pipestone of Devil's Lalce. 251 



THE PIPESTONE OF DEVIL'S LAKE. 



<Reacl before tlie Wiiconsin Academy of Sciences, Arts, and Letters, Februaij' 14, 1S7~.) 

 By E. E. Woodman, Baraboo. 



A rock found in the vicinity of D3vil's Lake has not, S3 far as 

 I am aware, been properly classified. The local and popular 

 nanne for it is soapstone, derived, doubtless, from several qualities 

 which it possesses in common with steatite, and especially the 

 greasy feel of that mineral. From the presence of the elements 

 of soapstone it is talcose, but the primary object of the present 

 paper is to identify it as an argillite of the variety called pipestone. 



Two specimens are herewith presented. The red one is from 

 the widely known quarry in south-western Minnesota, the other 

 from the neighborhood of Devil's Lake, Sauk county, Wisconsin. 

 On a superficial examination they will be found to possess several 

 properties in common. In their feel, hardness, susceptibility to 

 polish, earthy odor when moistened, freedom from grit, in most of 

 their obvious properties except color, they agree. Also their be- 

 havior before the blow-pipe is the same, both being infusible 

 without a flux, but with borax yielding a green glass. In these 

 characteristics they answer to the description which Nicollet 

 (Itinery 18i2, Senate Document No. 237) gives of the red pipe- 

 s';one of Minnesota, as quarried under his personal direction and 

 observation: "Compact; structure slaty ; receiving a dull polish ; 

 having a red streak; color blood reJ, with dots of a fainter shade 

 of the same color ; fracture rough ; sectile ; feel somewhat greasy ; 

 hardness, not yielding to the nail; not scratched by selenite, but 

 easily by calcareous spar ; specific gravity 2.90. The acids have 

 no action upon it; before the blow pipe it is infusible per se, but 

 with borax gives a green glass." 



I am indebted to Prof. W. W. Daniells, of this Academj^, for a 

 qualitative analysis of these specimens which completes the evi- 

 dence of their identity. He lind.s the principal component of 

 each to be silicate of alumina. This is combined with small 

 percentages of lime, magnesia and oxide of iron, the last being a 

 larger constituent of the red than of the gray specimen, as might 

 be inferred from its color. The specific gravity of the red speci- 



