Precious Opal Pseudomorphs after Gaylussite found in Tecopa
Dry Lake Sediments, Inyo County, CA
Robert Housley1, Marek Chorazewicz2, George
R. Rossman1
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125-2500, U.S.A. 2124 Pineplank Lane, Simi Valley, CA, U.S.A.
ABSTRACT
Tiny precious opals are abundant in siliceous nodules from certain
parts of the ancient Lake Tecopa sediments. The
precise arrangement of silica balls that leads to the intense play of
colors
was determined for a single sample by (Ma and Rossman
2003).More recently (Martin and
Gaillou 2018)
used isotopic measurements of oxygen and
hydrogen to argue that these opals formed under ambient conditions. We
have found searlesite blades in the same nodules in which the opal
occur.
