556 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



covellite. The source of sulfide appears to be sulfate- reducing bacteria 

 in the wood. Likewise, shapeless lumps found by Mr. Peterson in a 

 17th century Spanish shipwreck, also off Bermuda, were found to be 

 nearly pure covellite and appear to have been derived from copper or 

 bronze artifacts or fittings that came in contact with a source of sulfide 

 ion. Peterson suggests that some of the sulfide may come from gun- 

 powder stored in magazines of warships. Gunpowder is a mixture of 

 charcoal, saltpeter, and elemental sulfur. Lacroix (1910) observed 

 covellite mixed with clialcocite as an alteration product on copper 

 nails in a Eoman shipwreck off Mahdia, Tunis. Here again the sulfide 

 probably originated from bacterial decomposition of organic debris. 

 Mr. K. M. Organ ^ of the British Museum Laboratory says that 

 chalcocite was found on a bronze sword blade dated about 1,000 B.C., 

 taken from the river at Kings Lynn, Norfolk. A. Lacroix (1909) in 

 France over a half century ago described Roman bronze coins found in 

 a thermal spring at Grisy-en Saint Symphonen-de-Margne (Saone-et- 

 Loire) that had been transformed to black chalcocite which is sectile 

 and locally crystalline. Daubree (1881) also noted the occurrence of 

 a black form of chalcocite with metallic lustre on old copper coins from 

 thermal springs, which he called cupreine. A. Perinet (1961) found 

 chalcocite and digenite (CuoSs) among the alteration products on a 

 copper nail recovered from the ancient sunken wooden ship in the 

 Mediterranean off Grande Congloiie. 



COPPER NITRATES 



The occurrence of heavy metal nitrates in nature is rather rare 

 because of their solubility in water, although the nitrates of the alkali 

 metals, sodium and potassium, which are especially soluble, occur 

 abundantly in certain desert regions. Aoyama (1960, 1961) has identi- 

 fied basic copper nitrate, Cu(N03)2*3Cu(OH)2, among green corro- 

 sion products on copper electric powerlines in Japanese moimtain areas. 

 Although X-ray diffraction data is given, the exact mineralogical 

 species is not named. The writer has had the privilege of taking 

 samples of green crystalline corrosion products from bronze vessels 

 found by University of Pennsylvania archeologists in a royal tomb 

 at Gordion in Anatolia. Preliminary studies showed the crystals give 

 X-ray diffraction patterns identical with patterns of monoclinic syn- 

 thetic basic copper nitrates which have not yet been reported to occur 

 naturally. There may be new minerals yet to be identified among the 

 copper corrosion products of the numerous bronze vessels found at 

 Gordion. It is feared, however, that most of them have been lost by 

 premature cleaning. 



* Private cornnmnlcation. 



