1877 New Ser. 1 28 It is difficult to conceive how the agate-forming process could be continued after an impervious lining had once been thrown down upon the walls.
1966 50 28/1 Thus clay, potash, and agate-forming silica are added to the sedimentary minerals of the earth's crust.
2008 50 642 The unusual absence of quartzine suggests a low SiO2 concentration in the agate-forming solutions.