The Occurrence of an Unusual Type of Pisolite: The Cubic Cave Pearls of Castleguard Cave, Columbia Icefields, Alberta, Canada^∗

Abstract

Nests of calcite pisolites (“cave pearls”) of approximately spherical form are common features in caves. They grow by accretion of calcium carbonate around rolling nucleii. Nests of cubic pearls are rare. Four nests of cubic pearls are reported, but their development has not been explained.

A nest of cubic pearls in the Second Fissure, Castleguard Cave, is described in this paper. It contains more than 300 individuals in a two-layer orthogonal array. Laboratory analysis of one specimen indicates that it is composed of calcite and grew by accretion to an original spherical nucleus. It is proposed that development of the cubical form resulted from restriction of precipitate supply to the sides and base, a consequence of very regular packing. Very stable growth conditions are required, such as can only be found in certain underground sites.