  We describe a torsion pendulum with a large mass-quadrupole moment and a
resonant frequency of 2.8 mHz, whose angle is measured using a modified
Michelson interferometer. The system achieved noise levels of $\sim200\
\text{prad}/\sqrt{\text{Hz}}$ between 0.2-30 Hz and $\sim10\
\text{prad}/\sqrt{\text{Hz}}$ above 100 Hz. Such a system can be applied to a
broad range of fields from the study of rotational seismic motion and
elastogravity signals to gravitational wave observation and tests of gravity.
