MICA SWIRLS

Mica Swirls are transparent-based marbles that may be clear, various shades of green, brown, various shades of blue, gray, amethyst, red, or yellow. Within the glass are flecks of mica (muscovite) that may vary widely in size and amount (mica swirls with large amounts of mica are called "blizzards"). Usually, the mica will all swirl in the same direction, though it may also seem to float randomly within the marble.

Mica Swirls commonly contain "ghost" and/or "filament" cores. A ghost core is a group of tiny air bubbles all contained within an ethereal "sheath." Filament cores are typically green, and are thin strands that run straight from pontil to pontil. They are often within ghost cores but are sometimes alone, too. Other rare examples have exterior bands.