SISSVoc Default


definition Opal is a hydrated amorphous form of silica; its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Because of its amorphous character, it is classed as a mineraloid more like this
notation more like this
Opal more like this
source more like this
Resource original
Concept original
broader original
narrower opal original
in scheme commodity-code original
is primary topic of opal