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Silicified material examined for this study
| Formation (ref.) | Location | Age |
|---|---|---|
| Draken Formation (13) | Spitsbergen | Neoproterozoic |
| Rhynie Chert (14) | Scotland | Early Devonian |
| Olentangy Shale (15) | Ohio | Early Carboniferous |
| Serian Volcanic Formation (16) | Sarawak | Late Triassic |
| Morrison Formation (17) | Utah | Jurassic |
| Princeton Chert (18) | Alberta | Eocene |
| Vantage Sandstone (19, 20) | Washington | Miocene |
| Lost Chicken Creek Chert (1) | Alaska | Miocene/Pliocene |
