QXD - Quark Express Files
File Juicer can extract some images form Quark Express, but many will be damaged. Quark chops up the files in pieces and stores it in an internal format which is undocumented.
To extract images or text from Quark Express, I recommend Adobe Indesign which can open Quark files, and save them as PDF. The PDF can then be fed through File Juicer.
If you have Quark Express, you print to PDF directly and drop it through File Juicer afterwards.