﻿W. G. Brown — Crystallographic Notes. 379 



while the fifth is much smaller and its position is such as to 

 show the reentering angles markedly. Some of the crystals 

 consist of six individuals like fig. 5 in the paper cited, or more 

 like fig. 2 in a paper by Struver, "Ueber polysynthetische 

 Spinellzwillinge.''* Other forms still more complex resemble 

 those of spinel figured in the paper of Striiver referred to. 



Artificial crystallized cuprous oxide ( Cuprite). 



On the outside of the spongy portion of the metallic copper 

 just described there is a more or less continuous purple layer 

 of crystals of cuprous oxide (cuprite). These are individually 

 of a dark ruby-red color, with adamantine to sub-metallic 

 luster. 



The forms present are combinations of octahedron and cube 

 in all stages from dominant octahedron to dominant cube. No 

 simple forms were found. These crystals seem to have been 

 formed just when the solution in the cell had evaporated to the 

 level of the top of the deposited copper. They are confined to 

 a very narrow layer near the outside of the dendritic copper, 

 and are not pseudomorphs of the metallic copper, none of the 

 crystals being twinned or in any way resembling in habit those 

 of the metal among which they are found. 



Another example of crystallized cuprous oxide (cuprite) was 

 found on a camp spoon picked up near the site of a reserve 

 magazine on Morris Island, South Carolina, constructed by the 

 Federal forces when attacking Battery Wagner, entrance to 

 Charleston harbor, S. C, in 1863. The spoon is of german 

 silver, tarnished dull red and bronze, having spots of a green 

 salt of copper (silicate ?) over its surface where small cemented 

 groups and sprinkled grains of sand are firmly attached. Upon 

 the surface of the spoon there are several blisters. Upon open- 

 ing some of these, that part of the spoon beneath the blister is 

 seen covered with brilliant transparent crystals of cuprous 

 oxide (cuprite), showing only the faces of the octahedron, whose 

 triangular shape can just be distinguished by the unaided eye. 

 With a pocket lens they are distinctly visible. 



While there is nothing new in the formation of these crystals 

 on an alloy of copper, the short time in which the crystals have 

 formed seems a noteworthy feature of this occurrence. The 

 spoon could not have been exposed but little more than twenty 

 years, from 1863 to 1886. In all cases mentioned in the books f 

 the articles seem to have been exposed for a very long time to 

 natural agencies, and lead to the conclusion that the formation, 

 for example, on antique bronzes, under special conditions, is a 



* Zeitschrift fur Krystallographie und Mineralogie, Band ii, p. 480, and Taf. 

 XVII, fig. 2. 



\ For methods of production and occurrence, see Fouque et Levy, Synthese des 

 Mineraux et des Roches, p. 378, and Fuchs Die kunstlich dargestelltenMineralien, 

 p. 68. 



