Does Uranium ore count as a mixture?
Yes, uranium ore is a mixture.

Uranium compounds such as pitchblende (uraninite) are only present as a small part (usually $&lt;1$%) of the ore. 

Extensive purification is needed. Uranium ore purification would be a good choice for your project.

See for example:

http://www.areva.com/EN/operations-677/uranium-processing-from-ore-to-yellow-cake.html

http://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull23-2/23204882428.pdf



image source: http://chemwiki.ucdavis.edu/Development_Details/Approaches/ChemCases/Nuclear_Chemistry_and_the_Community/08._Uranium_Production