This sample is enriched with arsenic, and these pisolites show clear gold mineralization between their cortices (Mustafa and Tobia, 2010). Sedimentary ironstones in general can be naturally enriched in arsenic due to the abundance of iron bearing minerals and especially iron oxyhydroxides that have a high affinity for arsenic (Palumbo-Roe et al., 2005). The existence of broken pisolites that were acted as nuclii for larger compound pisolites suggests that such pisolites were formed in agitated water rather than within soil as a result of lateritization.