Assertion: calcite's crystal | /r/HasAspect | severe curves
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: Gypsum flowers most often exhibit simple twinning (known as contact twins); where parallel, long, needle-like crystals, sometimes having severe curves and bends, will frequently form “ram’s horns”, "fishtail", "arrow/spear-head", and "swallowtail" twins.