Assertion: opal's water | /r/CapableOf | percolate through porous rock
Facets:
Source sentences:
text: They form in the lava from the action of water percolating through the porous rock carrying silica in solution.
text: They form in gas pockets in the lava, which act as molds, from the action of water percolating through the porous rock carrying silica in solution.
text: The cooled bubbles were gradually filled by water percolating through the porous rock carrying rich quantities of silica (quartz).