Assertion: biotite | /r/CapableOf | vary in abundance
Facets:
value: considerably
type: DEGREE
Source sentences:
text: Both muscovite and biotite may be present and vary considerably in abundance; very commonly they have their flat sides parallel and give the rock a rudimentary schistosity, and they may be aggregated into bands in which case the granulites are indistinguishable from certain varieties of gneiss.