A mixture of chalcedonic (see chalcedony) silica SiO2 and hydrous silica SiO2.nH2O; occurs as flat, banded varieties with white, grey, brown, red, and black bands.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。