1007.] NATrUAL SCIEXCES OF PIIILADELPIHA. 445 



November 5. 

 Arthur Erwix Brown, D.Sc, Vice-President, in the Chair. 



One hundred and eight persons present. 



The death of Charles Mohr, INI.D., a member, October 31, 1907, was 

 announced. 



Notes on Minerals. — ^Ir. F. Lyxwood Garrison, exhibiting speci- 

 mens, remarked that Nos. 1 and 2 were copper ore, composed of 

 bornite, chalcopyrite in a hard, dense rock, determined microscopically 

 to be a tuff. These ores occur near the town of San Christobal, in the 

 island of. Santo Domingo, West Indies. There are at this place two 

 classes of copper deposits, one in veins or mineralized zones carrying 

 quartz and running in a definite direction through the country rock 

 (tuff). The other class is made up of segregations of chalcopyrite and 

 limonite in the tuff, and mostly located near the contact of the tuff 

 and the Cretaceous limestone. The two localities in which these 

 different ores occur are about a mile apart. A tlescription of these 

 deposits with a scientific dissertation thereon was published in the 

 Mining and Scientific Press of San Francisco, September 7, 1907, page 

 305. 



No. 3. ]\Iolybdenite with chalcocite and chalcopyrite, from the 

 Wallapi iMountains, Mojave Co., Arizona. The association of copper 

 ores with a relatively large proportion of molybdenite is exceedingly 

 rare. Molybdenite and copper minerals are sometimes found asso- 

 ciated together in gneiss, as for example at tlie Frankford quarries 

 near Philadelphia, but the combination of the two minerals in sufficient 

 amount to constitute an ore is, as far as he knew, unique. The country 

 rock containing these deposits is granite, probably not younger than 

 the Tertiary period. The district in which they occur is unexplored 

 in a geological sense, and was visited during July, 1907, by his assistant 

 engineer, Mr. William F. Ward. He hoped to have the opportunity 

 at a future time to examine this deposit and i)repare a more 

 elaliorate description of it. As a commercial matter it is highly 

 desiralDle to separate the molylxlenum from the copper minerals, but 

 as yet all attempts to do this have been unsuccessful. The molyb- 

 denum itself would bring a high price for use in making special steel, 

 since it is found to be more efficient for that purpose than tungsten, 

 chromimu or manganese. The jiractical commercial ]5roblem involved 

 in this proposition is to successfully separate the molybtlenum from the 

 copper minerals, as the presence of one would vitiate the other for use 

 in the arts. It is to be hoped that at some future time this can be 

 successfully accompUshc( 1 . 



