noun.
A translucent to transparent milky or grayish quartz with distinctive microscopic crystals arranged in slender fibers in parallel bands.
The Century Dictionary and Cyclopedia
noun.
A cryptocrystalline variety of quartz, resembling in color milk diluted with water, and more or less clouded or opaque with veins, circles, or spots.
the GNU version of the Collaborative International Dictionary of English
noun.
A cryptocrystalline, translucent variety of quartz, having usually a whitish color, and a luster nearly like wax.