Assertion: topaz | /r/PartOf | the sub-class nesosilicates
Facets:
Source sentences:
text: Topaz belongs to the sub-class Nesosilicates, the simplest of all silicates in which the tetrahedral SiO4 units exist separately, but are held together by metal cations as in Garnets, Andalusite and Olivine, or form cross linkages between chains of octahedrally co-ordinated aluminum cations, such as AlO4F2, AlO4F(OH), and AlO4(OH)2 , as in Topaz.