Adjective
not crystalline
Source: WordNetA glass is often not understood as a ceramic because of its amorphous (noncrystalline) character. Source: Internet
Noncrystalline opal Two broad categories of noncrystalline opals, sometimes just referred to as "opal-A", have been proposed. Source: Internet
Noncrystalline ceramics Noncrystalline ceramics, being glass, tend to be formed from melts. Source: Internet