274 Scientific Intelligence. 



copper which was formerly worked at Copper Harbor, Lake Superior, 

 but which was abandoned after some forty or fifty thousand pounds of 

 this very valuable ore had been raised. It was the only vein of this 

 substance, and perhaps the only locality known in the world, and speci- 

 mens will be highly prized by the mineralogist hereafter. The sub- 

 stance called copper-black, and sometimes black oxyd of copper, which 

 occurs in an earthy, pulverulent form, is not to be confounded with the 

 pure oxyd of copper found at Copper Harbor. Copper-black is a mix- 

 ture of various hydrated oxyds, especially of iron, manganese, and 

 copper, of which the latter forms but a small portion ; it occurs in an 

 incrustation on other ores of copper, and is evidently the result of their 

 decomposition. Semmola, however, has described a substance occur- 

 ring in small tabular crystals, belonging to the hexagonal system, which, 



according to him, are pure oxyd of copper, Cu. To this substance he 

 has given the name of Tenorite. The oxyd of copper found at Cop- 

 per Harbor is generally compact, though the purer specimens have a 

 crystalline structure. Mr. Teschemacher has, however, two specimens, 

 which he has kindly allowed me to examine, in which this substance is 

 distinctly crystallized in cubes, with their solid angles replaced. The 

 question arises, was the substance described by Semmola as crystallized 



? 



in the hexagonal system, really Cu, or is this substance dimorphous/ 



Some portions of the oxyd of copper from Copper Harbor are al- 

 most chemically pure, though it is generally mixed with a little silicate 

 of copper. One of the purest specimens contained only 12 per cent. 

 of impurities, mostly silica, with traces of lime and iron. 



As the oxyd of copper of this remarkable vein has not been miner- 

 alogically described, the following description is added. 

 ^ Substance tesseral, crystallized in cubes, with their solid angles occa- 

 sionally replaced; generally, however, massive, with crystalline struc- 

 ture, sometimes earthy; no traces of cleavage. H.z=3 ; G.=625; 

 color, steel-grey to black; lustre, metallic, the earthy varieties ac- 

 quire a metallic lustre on being scratched or cut with a knife ; opaque. 



Chemical composition Cu, almost pure ; containing copper, 79*86, oxy- 

 gen, 20- 13. 



3. On Arkansite. — This mineral which Mr. J. D. Whitney makes 

 out to be Brookite, has been examined by Mr. Teschemacher, (Proc. 

 Bost. Soc. N. H., April, 1849, p. 132,) and he gives the following for 

 its angles — see figure in this Journal, vol. iv, p. 279 — M : Mz=100° and 

 80°. M:c=l33° 35', c:c=135° 45', a:o=[2A°. Shepard made 

 M : M 101° to 101° 15', and a : a 123°. According to the measurements 

 of Mr. Teschemacher, the angles are those of Brookite* 



4. Baierine, (LMnstitut, No. 793.) — The metal pelopium has been 

 found in the Columbite of Bavaria, by G. Rose, and in that of Limoges 

 by Damour. It is proposed to distinguish this variety of Columbite by 

 the name baierine given it by Beudant. The specimens from these two 

 localities agree well in external characters and in analyses. 



5. Notices of American Minerals; by Prof. C. U. Shepard, (com- 

 municated for this Journal.) — Pyrophyllite in beautiful white stellce oc- 

 curs along with very brilliant and perfect crystals of rutile on a soft, 



# 



