Cave pearls in Carlsbad Cavern, New Mexico

Although long thought to be largely the result of physicochemical processes, speleothems are now recognized as potentially including a microbial component. Cave pearls, a type of speleothem, are coated grains that form in caves and mines. Three diverse cave pearl sites in Carlsbad Cavern, New Mexico, U.S.A., provide insight into physicochemical and microbial controls on cave pearl formation and, by analogy, other speleothems.  Pearl growth beneath active drips in the classic pearl nests of The Rookery was largely abiologic with autochthonous nuclei coated by laminae of columnar low-Mg calcite (LMC) alternating with laminae of LMC, high-Mg calcite (HMC), and aragonite.