About: http://webisa.webdatacommons.org/418919711

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Birefringence, which occurs naturally in crystals such as quartz and calcite, describes materials that have multiple indices of refraction, depending on what direction light enters the material.
http://www.w3.org/ns/prov#wasQuotedFrom	huffingtonpost.com