Noah Webster
Rock-crystal
ROCK-CRYS'TAL, noun The most perfect variety of silicious earth or quartz; limpid quartz. When purest it is white or colorless, but it is found of a grayish or yellowish white, pale yellow or citron. Its most usual form is that of hexagonal prisms, surmounted by hexagonal pyramids.
ROCK'-DOE, noun A species of deer.