Assertion: slate | /r/HasProperty | effective
Facets:
value: for decorative patterns
type: PURPOSE
value: on many 19th century roofs
type: LOCATION
value: in wet climates
type: LOCATION
Source sentences:
text: Slate is effective in wet climates but is expensive, heavy and may be easily broken when stepped on.
text: Because slate was available in different colors (red, green, purple, and blue-gray), it was an effective material for decorative patterns on many 19th century roofs (Gothic and Mansard styles).