Assertion: alexandrite's color | /r/CreatedBy | mineral impurities
Facets:
value: within the stone
type: LOCATION
Source sentences:
text: The base color of Moonstones is caused by mineral impurities that mixed with the Silicon and Aluminum chemicals as the crystals were being formed.
text: The colors of sapphires are caused by mineral impurities within the stone, for example titanium and iron create the blue in blue sapphires.