Assertion: mineral's crystal | /r/HasProperty | polished into lense
Facets:
value: for some of the earliest eyeglasses
type: OTHER
value: for hand magnifiers
type: PURPOSE
value: for telescopes
type: PURPOSE
Source sentences:
text: In the Middle Ages these crystals were cut and polished into lenses for hand magnifiers, telescopes, and some of the earliest eyeglasses.