Assertion: tourmaline | /r/HasProperty | semi-precious mineral
Facets:
Source sentences:
text: Tourmaline is a semi-precious mineral related to granite.
text: Tourmaline is a semi-precious gemstone.
text: Because tourmaline is a semi-precious material, adding tourmaline will increase a hair dryer’s cost.
text: Tourmaline is a semi-precious mineral which generates only negative ions when heated.