Assertion: matrix opal | /r/HasProperty | ironstone
Facets:
Source sentences:
text: Matrix Opals are silicified sandstone or ironstone which has opal forming within infillings of pores or holes or between grains of the host rock.
text: Matrix Opals are silicified sandstone or ironstone which has opal forming within infillings of pores or holes or between grains of the host rock.