Silicates were a large class of minerals based on a tetrahedral silicon-oxygen unit (SiO4).
The spaceborne organism nicknamed "Junior", discovered by the USS Enterprise-D in 2367, had an outer shell made from silicates, actinides, and carbonaceous chondrite. (TNG: "Galaxy's Child")
The lifeforms on L-S VI were based on silicates rather than carbon. (DS9: "The Alternate")
In 2374, the Silver Blood USS Voyager collected silicates from a comet in the Podaris sector. (VOY: "Course: Oblivion")