F. A. Canfield — Minercdogical Notes. 21 



owner having no recollection of its existence. The best 

 formed crystals were found at Colquechaca. The piece that 

 Professor Penfield analyzed came from Porco, but the crystals 

 that he examined, and from which he determined the true 

 crystalline form of the mineral, were found at Colquechaca. 



III. Canfieldite. — In the description of this species by Pro- 

 fessor Peniield the locality is given as La Paz, Bolivia.* The 

 writer having a personal interest in canfieldite, has endeavored 

 to find its true locality, feeling certain that it was not La Paz. 



Mr. William E. Hidden, who furnished the specimen that 

 Professor Penfield examined, told the writer that.it was sent 

 to him by a collector in La Paz, but that he had no reason for 

 thinking it was found in or near that city. By correspondence 

 with friends in La Paz, and by personal interviews with resi- 

 dents of that city, the writer has found no evidence that there 

 is any active silver mine nearer La Paz than Oruro, which is 

 150 miles distant. 



Bolivia is a peculiar countiw ; nearly the entire white popu- 

 lation is concentrated in a few large cities, which are widely 

 scattered. The weekly parcels post and the freighters make it 

 easy to transmit samples and cargoes of ores to the important 

 business centers. The writer saw collections of ores, from the 

 various mining districts, in every large town that he visited. 

 He got his best specimen of pyrargyrite in La Paz, but it 

 came from Colquechaca. The type crystals of argyrodite 

 were secured in Potosi, while the largest mass of this mineral 

 was obtained in Sucre from the owner of a mine in Porco. 

 Many similar cases could be given, but this is a sufficient 

 explanation how any particular specimen could be found in 

 La Paz. This is negative evidence. When in Colquechaca in 

 1887, the w T riter was presented with a specimen of canfieldite 

 by the manager and part owner of a mine, in his office, at the 

 entrance of the main adit of the mine, so there can be no 

 question as to its locality. The principal crystal is much 

 smaller than the one in the Brush Collection, but otherwise 

 its appearance is identical with the type crystal, even to the 

 line of twinning that is seen on the faces of the rhombic 

 dodecahedron. As there is no direct evidence that this min- 

 eral has been found at any place besides Colquechaca, it is but 

 reasonable to conclude that the type crystal came from the 

 mines in that place. 



The specimen obtained by the writer at the mine in Col- 

 quechaca is a group of crystals of pyrargyrite with wire silver. 

 Many crystals of canfieldite are scattered over the pyrargyrite. 

 Most of them show on the dodecahedral faces the depression 



* This Journal, xlvii, 451. 



