21. The skeletal material consists of amorphous silica ( opal A ). 22. The sponge sediments have high levels of silica and organic carbon. 23. Furthermore, grasses and annual plants often have high silica contents. 24. Documentation and photography are displayed from the local communities of Silica . 25. Silica is non-conductive and therefore not detectable by conductivity.26. She then joined the silica content and the hardness of wood. 27. Wolff originated the development of all-silica tire tread compounds. 28. The compound is added to rubber compositions that contain silica filler. 29. The sulfate concentration ranged from and the silica concentration ranged from. 30. But his silica -lined converter has been superseded by the improved
