C. U. Shej>ar(rs Reply to F. A. Genlh. 41 



But it is important to notice that Dr. Genth is half, inclined to 

 admit Scheerer's variety Avith a cubical cleavage, found at Telle- 

 mark in Norway, as a genuine species; which certainly well 

 explains au observation he makes upon harrisite : — '' The emi- 

 nent cleavage of this pseudomorph in the form of the original 

 mineral has for a long tune perplexed aud kept me in doubt, 

 whether, it might not be a good species after all, but t]ie more 

 carefully I have examined the specimens in m}^ possession, and 

 those of the Canton mine, the more have I become convinced 

 that it is a pseudomorph." The results of this examination and 

 the grounds of his conviction, have been presented and com- 

 mented upon, above. 



My mention of plumbo-resinite at this locality meets the fol- 

 lowing pointed * criticism : — '' ShepaviTs Plumho- Resinite from the 

 Canton mine is Cyanosite, I am indebted (observes Dr. G-.) to W. 

 F. Harris, Esq., wdio had the advantage of Prof. C. U. Shepard's 

 own mineralogical determinations for a genuine specimen of 

 what the latter in his report on the Canton mine calls Plumbo- 

 resinite." 



It is wholly and entirely an error to say, that Mr. Harris had 

 any other means of knowing what I had called plumbo-resinite, 

 than could be gathered from the few words in which it was men- 

 tioned in the report. I had not detected the mineral when at 

 the mine ; but only after my return from it, to Charleston ; and 

 I have never communicated either by letter or specimens, with 

 the gentleman mentioned, upon the subject. The specimens 

 employed in my determination are now arranged in my mineral- 

 ogical cabinet at Amherst, Mass., where any one who may 

 choose to examine them, will easily form an opinion how un- 

 likely it must have been, that I could ever have committed the 

 mistake of confounding such a substance, with the common blue- 

 vitriol incrustations of the Canton mine. 



The next of my minerals reexamined by Dr. Gentli is the 

 Hitclicockite, The mining report does little besides announcing 

 its existence and the reason of its name. It mentions it as a 

 white, earthy crust or shell, whose composition was that of a 

 hydrated phosphate of alumina, with oxyd of zinc ; and it 

 eemed most natural in an economical report, to include it alon^ 

 with automolite under the general heading of ores of zinc, not 

 supposing that any candid mind would possibly infer therefrom, 

 that I regarded it, as a working ore of that metal. Indeed I 

 supposed that my language would rather convey the idea, that 

 the oxyd of zinc was an unimportant, if not an accidental, con- 

 stituent of the substance. 



But to show what I regarded as a more satisfactory account 

 of the mineral, I here subjoin my description of it, drawn from 

 my Mineralogy (p. 401): 



SECOND SERIES, VOL. XXTVy NO. 70. — JULY^ ISOT. 



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