P. Stoffynegli et al., CORROSION OF BRASS IN A MARINE-ENVIRONMENT - MINERAL PRODUCTS AND THEIR RELATIONSHIP TO VARIABLE OXIDATION AND REDUCTION CONDITIONS, Applied geochemistry, 13(5), 1998, pp. 643-650
Minerals coating brass ammunition shells that rested at the bottom of
Halifax Harbour, Nova Scotia, for 52 a have been identified by X-ray d
iffraction and analytical scanning electron microscopy. The admiralty
brass shells, partially buried in anoxic muds, straddle a strong Eh gr
adient ranging from 0 mV to values characteristic of oxygenated seawat
er. Whereas the brass surface in contact with the sediment has been pr
eserved, parts of the shells exposed to seawater have corroded through
out their thickness. The corrosion products identified include metalli
c Cu, djurleite (Cu1.96S), cuprite (Cu2O), atacamite (Cu2Cl(OH)(3)), s
pertiniite (Cu(OH)(2)) and hydrozincite Zn-5(CO3)(2)(OH)(6)). These pr
oducts are those predicted thermodynamically on the basis of ambient E
h and pH. However, this study also revealed the presence of a mineral
not previously known to exist and tentatively identified as CU14Zn14Cl
5(SO4)5(OH)(41 .)H2O This ''new'' mineral seems to have a stability fi
eld in Eh-pH diagrams similar to that of connellite (CU19Cl4(OH)(32 .)
2H(2)O). (C) 1998 Elsevier Science Ltd. All rights reserved.