Genesis of Oolite and Pisolite Grains: An Energy Index

Cave Pearls--The Integrated Product of Abiogenic and Biogenic Processes

“…Unattached spherical bodies formed of a nucleus encased by concentric cortical laminae are common in pools and depressions on the floors of many caves. Usually formed of calcite and rarely aragonite (Forti et al 2006), these coated grains have been called concretions (Stone 1932;White 1976, p. 298;Pentecost 2005, p. 71), cave pearls (Hess 1930;Kirchmayer 1969;de Swart 1972;Kirchmayer 1987;Woo et al 2008), or cave oolites/pisolites/pisoliths/pisoids (Pond 1945;Baker and Frostick 1947;Coleman 1949;Barczyk 1956;Donahue 1969;Roberge and Caron 1983). This plethora of names has arisen through casual labeling of these grains and debate over their mode of origin.…”

“…The term ''cave pearl'' appears to have been applied largely to those forms with a polished exterior (e.g., Mackin and Coombs 1945;Baker and Frostick 1947). Attempts to portray the nature of these concretionary grains more precisely have utilized terms such as cave oolites, cave pisolites, cave pisoliths, and cave pisoids (Pond 1945;Baker and Frostick 1947;Coleman 1949;Baker and Frostick 1951;Barczyk 1956;Donahue 1969;Dunham 1969;Roberge and Caron 1983;Jones and MacDonald 1989). Hill (1992, her Table 1), who compared pisoliths and cave pearls, argued that ''Cave pearls are not in any way related to sedimentary rocks'' but suggested that ''…cave pearls are a type of pisoids…''.…”

Petrographic and geochemical study on cave pearls from Kanaan Cave (Lebanon)

“…According to Baker & Frostick (1947) and Donahue (1969) the Kanaan spherical to subspherical concretions, which have smooth (polished) and lustruous shining surface, may be termed "cave pearls" and are believed to have formed in agitated water. Donahue (1969) related the genesis of ooid and pisoid grains to the prevailing energy (agitated versus nonagitated conditions).…”

“…Donahue (1969) related the genesis of ooid and pisoid grains to the prevailing energy (agitated versus nonagitated conditions). The 'agitated grains' were, thus, characterized by distinct concentric laminations, a pseudo-uniaxial cross (under polarized view), nucleus, smooth polished surfaces, low insoluble residue.…”

“…The great majority of the observed cave pisoids show an external smooth, wellpolished, lustrous morphology ( Fig. 3C) -advocating their classification as 'cave pearls' (Baker & Frostick, 1947;Donahue, 1969;Hill & Forti, 1997). Less commonly, some cave pearls show rough, irregular crenulated surfaces made up of tiny trigonal calcite crystals (Fig.…”