Quartz is a mineral that's usually clear or white, but is sometimes tinted a translucent color. It's common for quartz to be part of other rocks, and often you can see its stripes cutting through smooth beach stones.

Quartz is very hard and shiny, and it's also quite common. There are many different types of quartz, and the rarest ones are considered semi-precious gemstones, like citrine and amethyst. This is the quartz that's used to make jewelry. Its chemical name is silicon dioxide, and it has a crystal structure. Quartz comes from the German Quarz, "rock crystal."

Definitions of quartz
  1. noun
    a hard glossy mineral consisting of silicon dioxide in crystal form; present in most rocks (especially sandstone and granite); yellow sand is quartz with iron oxide impurities
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    quartz crystal
    a thin plate or small rod of quartz cut along certain lines and ground so that it can produce an electric signal at a constant frequency; used in crystal oscillators
    rock crystal, transparent quartz
    a clear quartz used in making electronic and optical equipment
    cairngorm, smoky quartz
    a smoky yellow or brown quartz
    a transparent purple variety of quartz; used as a gemstone
    calcedony, chalcedony
    a milky or greyish translucent to transparent quartz
    semiprecious yellow quartz resembling topaz
    rose quartz
    a translucent rose-red variety of quartz used for ornaments
    aventurine, sunstone
    a translucent quartz spangled with bits of mica or other minerals
    common topaz, false topaz, topaz
    a yellow quartz
    an imitation diamond made from rock crystal or glass or paste
    an impure form of quartz consisting of banded chalcedony; used as a gemstone and for making mortars and pestles
    bloodstone, heliotrope
    green chalcedony with red spots that resemble blood
    carnelian, cornelian
    a translucent red or orange variety of chalcedony
    a green variety of chalcedony valued as a gemstone
    aventurine spangled densely with fine gold-colored particles
    a chalcedony with alternating black and white bands; used in making cameos
    a green slightly translucent variety of chalcedony used as a gemstone
    sard, sardine, sardius
    a deep orange-red variety of chalcedony
    type of:
    solid homogeneous inorganic substances occurring in nature having a definite chemical composition
  2. noun
    colorless glass made of almost pure silica
    synonyms: crystal, lechatelierite, quartz glass, vitreous silica
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    type of:
    natural glass
    magma of any composition that cooled very rapidly
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