92 W. Lindgren — Gold Deposit at Pine Hill, Cal. 



The influence of the specific gravity in the case of liquids 

 heavier than water is much more marked than in the case of 

 those lighter than it. Thus the table shows that with the ex- 

 ception of the benzene derivatives, the drop-sizes diminish 

 quite regularly, as the specific gravities increase. The anomaly 

 in the behavior of the benzene molecule is undoubtedly due to 

 its constitution. 



The foregoing work was performed with the purpose of 

 developing and testing methods, rather than that of accumula- 

 ting data; it is to be regarded as a series of " orientation " ex- 

 periments, which have shown in what direction it is best 

 to continue. Investigations of this sort will certainly throw a 

 much clearer light upon the nature and workings of the molec- 

 ular forces, a knowledge of which is of the greatest importance. 



Chicago, 111. 



Art. XII. — The Gold Deposit at Pine Hill, California; 

 by Waldemar Lindgren. 



General Type. — Veins and seams of barite, carrying gold 

 and silver, distributed through a kaolinized zone in diabase 

 and diabase porphyrite. 



The auriferous deposits of California have, as well known, 

 two principal modes of occurrence : Secondary as gold-bearing 

 gravels and sands of Tertiary or Pleistocene age, and primary 

 as fissure veins, largely of late Mesozoic age. The latter occur 

 in great variety of formations, but on the whole, avoid the 

 large granite areas and seem to prefer the contact of sedi- 

 mentary slates with eruptive, unaltered, or dynamically meta- 

 morphosed masses. The form of the auriferous veins also 

 varies considerably between normal, regular fissure veins and 

 networks of minute irregular fractures. 



With all diversity in surroundings and form, the vein mate- 

 rial or gangue and the mineral associations are simple and sub- 

 ject only to rare and slight variations. The gangue is nearly 

 always quartz, the mineral association native gold, sulphides of 

 iron, copper, lead, and zinc, — frequently also arsenical pyrites, 

 rarely tellurides. Dolomite and calcite accompany the quartz 

 at certain veins, but even then the quartz is usually the princi- 

 pal ore carrier.* 



* The association of native gold with calcite in Shasta County, California, has 

 been noted by Mr. G-. F. Becker (Statistics of the Precious Metals, Tenth Census, 

 vol. xiii, p. 24), and from Trinity County, California, by Mr. J. S. Diller (this 

 Journal, vol. xxxix, 1890, p. 160). 



