  We relate the semiclassical asymptotics of the 6j symbols for the
representation theory of the quantized enveloping algebra U_q(sl_2) at q a
primitive root of unity, or q positive real, to the geometry of non-Euclidean
tetrahedra. The formulas are motivated by the geometry of conformal blocks in
the Wess-Zumino-Witten model; they generalize formulas in the case q = 1 of
Wigner, Ponzano and Regge, and Schulten and Gordon, proved by J. Roberts.
