The mineral gaudefroyite contains parallel chains of linked MnO6 octahedra. The Mn magnetic moments order with parallel spins within a given chain at low temperature, but the geometric arrangement of the chains restricts order between them - magnetic effects are "frustrated" and no order occurs, at least not until very low temperatures. It has been predicted that properties of this type may provide materials for efficient magnetic cooling - the "magnetocaloric effect". We have now shown that this material can indeed provide such refigeration at 20 K, a temperature which would allow more efficient liquefaction of hydrogen than other materials. We therefore now need to obtain better knowledge of the magnetic properties of this mineral at low temperatures - does it order at very low temperatures and to what extent can the moments be controlled by small magnetic fields.