52 The American Naturalist. [January, 



Fig. 4. — Hoplophoneus primaevus. 

 Fig. 5. — Hoplophoneus robustus. 

 Fig. 6. — Hoplophoneus insolens. 

 Fig. 7. — Hoplophoneus occidentalis. 



All XI 



The Goldbearing Quartz of California.— The salient charac- 

 teristics of the gold quartz veins of California are briefly given by Mr. 

 Waldemar Lindgren in a paper recently published, and the results of 

 his observations are thus summarized : 



"The auriferous deposits extend through the state of California 

 from north to south, in an irregular and unbroken line. 



" The gold quartz veins occur predominantly in the metamorphic 

 series, while the large granitic areas are nearly barren. The contact 

 of the two formations is not distinguished by rich or frequent deposits." 



"The gold quartz veins are fissure veins, largely filled by silica 

 along open spaces, and may dip or strike in any direction. 



" The gangue is quartz, with a smaller amount of calcite ; the ores 

 are native gold and small amounts of metallic sulphides. Adjoining 

 the veins, the wallrock is usually altered to carbonates and potassium 

 micas by metasomatic processes. 



" The veins are independent of the character of ;the country rock, 

 and have been filled by ascending thermal waters charged with silica, 

 carbonates and carbon dioxide. 



" Most of the veins have been formed subsequent to the granitic in- 

 trusions which closed the Mesozoic igneous activity in the Sierra Ne- 

 vada." 



Regarding the origin of the gold, the author speaks with reserve. 

 He points out the possibility of its derivation from the surrounding 

 rocks, which theory, however, is not altogether satisfactory. He then 

 states the following facts and the conclusion based upon them : 



* First, the gold quartz veins throughout the state of California are 

 closely connected in extent with the above described metamorphic 

 series and that the large granite areas are almost wholly void of veins, 

 though fissures and fractures are not absent from them. 



"Second, that in the metamorphic series the gold quartz veins occur 

 in almost any kind of rock, and that if the country rock exerts an in- 

 fluence on the contents of the veins, it is, at best, very slight. 



" Third, that the principal contact of the metamorphic series and the 

 granitic rocks is in no particular way distinguished by rich or frequent 



