﻿E. & Dana — Crystallization of Gold. 135 



branching off from another line at the bottom ; here the second 

 line of crystals parallel to the first is concealed from view, but 

 the third is shown consisting of those elongated in the direction 

 of the other axis. These last are represented as having the 

 same rhombohedral development as the others, which is often 

 true, but it is also common to find them with this elongation 

 scarcely shown so that they deviate much less from the ordi- 

 nary trisoctahedral form. These threads are then made up of 

 the line or lines of sharp rhombohedral forms and this other 

 line of minute bead-like crystals. These compound threads 

 often taper down to a fine wire with crystalline markings on 

 the surface but showing no distinct forms. 



No fullness of description could give a satisfactory idea of 

 the variety of these forms, as no drawing could adequately 

 represent their beauty and delicacy. The arborescent branch- 

 ing forms are the most beautiful. Here we pass from examples 

 where from a single stem a series of little lines run off, to 

 others where the branching is again repeated, and yet again 

 with such perfection that each individual crystal can be clearly 

 made out. Other forms take the shape of a feather with a 

 strongly defined central axis and with the fine threads branch- 

 ing from it on both sides at a slightly oblique angle (o^o=70° 

 S2 ; ). The central line is here normal to a plane 111, while the 

 branches go off in directions normal to 111 and In respectively ; 

 in all cases we have to do with parallel grouping only, and 

 there is no necessity to appeal to twinning to explain the forms 

 observed. The only distinct examples of this method of 

 growth in gold, which the author has been able to observe, are 

 these from the Oregon mine, with the exception of a single 

 Hungarian specimen in the cabinet of Mr. Clarence S. Bement 

 of Philadelphia, which appears to be developed in a similar 

 manner. 



2. Gold from California. 



The gold mines of California have produced large numbers 

 of specimens of finely crystallized gold, but unfortunately it is 

 only rarely that they have been preserved. But little has been 

 published upon the subject ; a recent article somewhat popular 

 in character, by W. P. Blake* of New Haven, is deserving of 

 mention. The specimen to which the writer's attention was first 

 directed belongs to the Yale collection, and is labeled as having 

 come from Tuolumne County. It consists of a series of octa- 

 hedrons in parallel position, and passing from the small solid 

 crystals to larger ones with cavernous faces and their edges in 

 ridges, and then to others looking as if they had been made of 

 bent wire. In addition to the large octahedral faces (o), there 



* The various forms in which gold occurs in nature, 25 pp. ; from the Report 

 of the Director of the U. S. Mint for 1884. 



