MINERAL l^RODUCTS. 23 



Coal. — A remarkable form of coal, closely resembling cannel coal, is found in connexion with 

 the cretaceous strata on the Kio Grande, being exposed at several points along the course of the 

 river from the mouth of the Pecos to Laredo. The character of the formation and economic 

 value of the product, as an article of fuel, will be given in the report of Mr. Schott. 



Salt occurs in connexion with salt lakes, occupying depressed portions of the wide desert 

 tracts, to which the term of Llano Estacado is applied. The product is more or less pure, and 

 in greater or less abundance, according to obvious local causes. 



Gypsum occurs in connexion with marls, belonging either to the upper Tertiary, or alluvial 

 series of deposits. In such situations it frequently forms very extensive beds, composing the 

 main bulk of local table-land exposures. 



In concluding this report, I have to express my special obligations to Professor James Hall, 

 of Albany, who has kindly favored me with his views of the geological collections of the survey, 

 and otherwise rendered assistance in making out this report. Similar acknowledgments are 

 due to Professor John Torrey, of New York, in reference to the botany. 



Especially, in this final conclusion of my duties on the Mexican boundary survey, are my 

 sincere thanks due to Major W. H. Emory, with whom I have been directly associated, in field 

 and office duties, for the last five years, a length of time signalized by repeated and considerate 

 acts of kindness on his part, as my superior officer^ and gratefully remembered on mine. 



Eespectfiilly submitted. 



C. C. PAKRY, M. D., 

 Botanist and Geologist U. S. B. 0. 



I consider the present a proper place to insert the analysis of minerals, not only of those 

 referred to by Dr. Parry in the above memoir, but those which were collected in the new Terri- 

 tory subsequently to his withdrawal from the commission. 



In the Organ Mountains, near Fort Fillmore, and at several other places along our route, 

 silver mines have been opened by enterprising Americans, but I have not obtained analyses of 

 the minerals procured at them, for the obvious reason that the experience of the miner will be 

 a more valuable test of the value of the mine than any which can be afibrded by specimens. 



Nothing can be a more fallacious test of the value of a mine than the analysis of pieces of ore 

 taken at random from the metallic vein, as most of these have been. Its true value can only be 

 arrived at by actually working the mine, which, for the purpose of experiment, may be carried 

 on upon a very limited scale. 



Those familiar with the localities will see in the analysis that si)ecimens from veins of known 

 value are here exhibited as yielding a very low per cent, of precious metal. These specimens 

 are therefore not fair examples of the whole. 



"When at Janos, I observed the inhabitants collecting nitre from the soil by the rudest process, 

 and was informed that all the powder used in blasting at the mines of San Pedro was manufac- 

 tured from the nitre thus obtained. The soil, in many places almost destitute of vegetation, is 

 no doubt surcharged with this substance, and a portion of soil was collected to be analyzed, and 



