ABSTRACTThe copper sulfate minerals chalcanthite (CuSO4.5H20), antlerite (Cu3SO4(OH)4), and brochantite (Cu4SO4(OH)6) are observed as corrosion products on copper alloy objects such as statues which are exposed to weathering. The usual product in aqueous corrosion is brochantite, though posnjakite (Cu4SO4(OH)6H20) is also known. No copper sulfate mineral is commonly found in artifacts recovered from near-surface burial. These observations can be explained in terms of stability diagrams and microbiological activity.
Summary This copper alloy crucifix was found during excavation at Macewen's Castle in Argyll in 1968 and closely resembles others known to date from the 12th century; it may have been made in Belgium. The arms could have been bent back to aid concealment in the 17th or 18th centuries.
Electrochemical Corrosion Performance of FSSP-Modified Copper Alloy Surface