Barbertonite
Barbertonite is a magnesium chromium carbonate mineral with formula of [Mg6Cr2(OH)16CO3·4H2O]. It is polymorphous with the mineral stichtite and, along with stichtite, is an alteration product of chromite in serpentinite. Barbertonite has a close association with stichtite, chromite, and antigorite (Taylor et al., 1973). A study published in 2011 presented evidence that barbertonite is a polytype of stichite and should be discredited as a mineral species.