226 UNIVERSITY OF VIRGINIA PUBLICATIONS 



an intense blue when heated on charcoal and touched with a cobalt solu- 

 tion; is soluble in sulphuric, nitric, and hydrochloric acids; and in the 

 fluxes may show a trace of iron ; while also calcium is frequently detected, 

 but never fluorine — and has a specific gravity under 2, and a hardness of 

 3 to 3.5 — it is very safe to call it evansite. It may be further checked by 

 a chemical analysis when its various constituents will be found to be as 

 follows and close to or within the limits assigned immediately below. 



Constituents Per cent limits 



AI2O3 36.0 - 38.5 



P2O5 19.0 - 22.0 



F2O3 0.5 - 6.0 



CaO 1.0- 4.0 



MgO trace - 1.0 



Ignition loss (H2O) 36.0 - 38.5 



Evansite is known to occur at but two points in America and these 

 widely separated. It was first discovered in this country, as previously 

 stated, in Alabama and later in Idaho. Specimens were collected from the 

 Idaho locality, situated in the vicinity of Goldburg, and sent to the U. S. 

 Geological Survey by Mr. C. R. Potts. The mineral found there is re- 

 ported* as occurring in seams and as being "massive amorphous" and "very 

 brittle with a conchoidal fracture." "Its hardness is about 3, and its color 

 is generally brown, though it varies considerably. Some specimens are 

 yellow, or white, or dark red." On the other hand the evansite from Ala- 

 bama is found as a white to slightly resinous coating with clusters developed 

 here and there in the shape of small batryoidal surfaces. 



The Alabama deposit of evansite is unusual because of its being found in 

 association with coal which probably is the only occurrence known where it 

 is found in this association. The mineral was discovered some years also 

 in sinking a shaft on the highly tilted (D. 57° S. E. and S. N. 40° E.) Martin 

 coal seam of the Coosa coal field where it outcrops about one-half of a mile 

 west of Coalville, Alabama, in the N. E. f of the N. W. i of S. 4, T. 20, 

 R. 1 W. The locality in question is not situated just west of Columbiana 

 as reported by Schallerf and Catlett,t but on the contrary is much more 

 north than west of there, since Coalville is 11 miles N. 13° W. from Colum- 

 biana, the county seat of Shelby County, Alabama, while the road from the 

 latter (Columbiana) to the Big Narrows (the transverse valley cut by the 



* U. S. G. S. Bull. 490. 

 t V. S. G. S. Bull. 490. 

 tA. I. M. E. Bull. 59. 



