Magnetic order is a property of crystalline materials which contain systems of coupled magnetic moments. In materials known as geometrically frustrated magnets there exist coupled magnetic moments but they do not order because there is no one ordering pattern which is more favourable than others. Materials having the cubic pyrochlore structure often behave like this. We have studied a cubic pyrochlore containing osmium and found evidence for magnetic correlations but no magnetic order down to 1.6 K. Osmium in this material is special because the moment tends to fluctuate due to quantum mechanical entanglement of spin and orbital angular momentum. We will use muon spin relaxation to determine whether our osmium pyrochlre orders magnetically below 1.6 K, and to try to understand whether magnetic frustration and quantum fluctuations are responsible for the suppression of magnetic order.