High Cristobalite and High Tridymite in a Middle Eocene Deep-Sea Chert

Science  22 Aug 1975:
Vol. 189, Issue 4203, pp. 631-632
DOI: 10.1126/science.189.4203.631


The high-temperature forms of cristobalite and tridymite have been found occurring in a Middle Eocene, radiolarian-rich claystone. Evidence indicates that these crystals formed at low temperature and were chemical precipitates. Scanning electron microscopy, energy-dispersive x-ray analysis (microprobe), and x-ray diffraction provided the data upon which the determinative mineralogy was based.