1890.] MICKOSCOPICAL JOURNAL. 233 



A Rare Specimen of Crystallized Gold. 



By henry G. hanks. 



SAN FRANCISCO, CAL. 



[Read before the Microscopical Society, August 27, 1890.] 



This specimen was found in Summit county, Col., in 1887. The 

 " Gold Crystal Mine," from which it was taken, is what is known to 

 rhiners as a " pocket mine," and the variety, " seam diggings." The 

 seam lies in black slate, and is associated with red oxide of iron, prob- 

 ably changed from pyrites. The auriferous portion varies from the 

 thickness of a knifeblade to six inches. The specimen occurred at the 

 junction of two seams of the same character. Coarse gold had been 

 panned out near by, which encouraged the miners to drive a tunnel 

 leading to the discovery of the seam. 



The weight of this specimen is 92 7 Troy ounces ; extreme length, 

 7 inches; width, 5 1-16 inches; thickness, 3 indies; specific gravity, 

 7.1^1368 -|-; fineness of the gold, 814; fineness of the silver, 150; value 

 of the gold per ounce, $16 82. 



In excess of its intrinsic worth it has high scientific value, and it is 

 to be hoped it will find an honorable position in some national museum, 

 for it would be an insult to nature and a serious loss to science to send it 

 to the melting pot. The beauty of the crystals, of which it is almost 

 wholly composed, could not be fully appreciated without the aid of our 

 favorite instrument. While to the eye it is a beautiful and interesting 

 object, it is simply wonderful when its crystallographic details can be 

 studied under an amplification of from twenty diameters upward. Many 

 of the faces, when so magnified, assumed the form of depressed panels, 

 a rare peculiarity of gold, although before noticed by mineralogists. 

 The crystals were generally small, and not all perfect ; but their details, 

 both as individuals and in groups, are worthy of careful study. 



The condition of the crystals would indicate deposition in the vein 

 by slow accretion, from a fluid holding gold in solution. It was not 

 possible that such a specimen could result from fusion and subsequent 

 crystallization while the mass slowly cooled, an opinion held by some 

 geologists. 



Recently J- O. Whitney brought a fine lot of nugget gold from the 

 Scott river hydraulic mine, in Siskiyou county. While the specimens 

 did not equal the above in beauty, they were not deficient in avoirdu- 

 pois, and the object lesson they teach is no less interesting. On exam- 

 ining the golden pebbles they were found to be simply rounded masses 

 of bright, yellow gold, without the least trace of crystal, wire, or leafy 

 form peculiar to the same metal in quartz. 



o 



The Relation of Bacteria to Practical Surgery. — The Times 

 and Register^ of July 19, 1890, contains a paper by John B. Roberts, 

 M. D., with the above title, which is well worth any physician's read- 

 ing- . 



It is a plain statement, without needless technicality, of the points in 

 bacteriology which are of value to the practical surgeon — the best re- 

 sume of the kind that we have yet seen. The only exception we take 

 to the paper is the acceptance of phagocytosis as a proven fact. 



