Assertion: silica's form | /r/HasProperty | described
Facets:
Source sentences:
text: A brown, powdery, amorphous form of silicon has been described that also has a microcrystalline structure.
text: A non-occupational form of silicosis has been described that is caused by long-term exposure to sand dust in desert areas, with cases reported from the Sahara, Libyan desert and the Negev.