A lithium depletion boundary is detected in HIP 112312 ( GJ 871.1 A and B ) , a \sim 12 Myr old pre-main sequence binary system .
A strong ( EW \approx 300 mÅ ) Li 6708 Å absorption feature is seen at the secondary ( \sim M4.5 ) while no Li 6708 Å feature is detected from the primary ( \sim M4 ) .
The physical companionship of the two stars is confirmed from common proper motions .
Current theoretical pre-main sequence evolutionary models can not simultaneously match the observed colors , brightnesses , and Li depletion patterns of this binary system .
At the age upper limit of 20 Myr , contemporary theoretical evolutionary models predict too slow Li depletion .
If true Li depletion is a faster process than predicted by theoretical models , ages of open clusters ( Pleiades , \alpha Persei , and IC 2391 ) estimated from the Li depletion boundary method are all overestimated .
Because of the importance of the open cluster age scale , development of self-consistent theoretical models to match the HIP 112312 data is desirable .