(S/E) When you reach the Col de Jau, the Callau Refuge is clearly signposted. Just follow the track south, but with the thick snow, it is possible to stray from it without realising.
(1) Once you reach the refuge, it is advisable to continue to the other pastoral refuge, located two hundred metres further on, then climb up to the right towards the old talc mine, of which practically nothing remains.
(2) The return journey follows the same route (due to the depth of snow, which makes it impossible to cross the forests). Return to the car park (S/E)

. Thank you for this lead.