Sikaris
From Star Trek : Freedom's Wiki
Sikaris was a planet in the Delta Quadrant and was the homeworld of the Sikarians. It had a mantle of tetrahedral quartz twenty kilometers thick, which served as an amplifier for the Sikarians' spatial trajector technology.
The USS Voyager visited Sikaris for shore leave in 2371 at the invitation of the Sikarians. (VOY: "Prime Factors")