  UBe13 was the second discovered heavy fermion superconductor, and numerous
pieces of evidence exist that imply that it is an unconventional (non-BCS,
non-s wave pairing symmetry) superconductor. Exhibiting even more signs of
unconventional superconductivity, Th-doped UBe13 is perhaps the most puzzling
of any of the unconventional superconductors. This review considers both the
parent, undoped compound as well as the more interesting Th-doped UBe13. After
summarizing the rather thorough characterization, which because of the interest
in these compounds has continued from their discovery in 1983 and 1984 to date,
these properties are compared with a recent template for determining whether a
superconductor is unconventional. Finally, further experiments are suggested.
