Those look like 'water stains.' It's the trace elements left behind by water & fertilizer after evaporation - mostly salts. You can remove them with a damp paper towel or sponge. Build up accumulation of this over time could be detrimental to your plant. It's a good idea to periodically let your plant sit under a running water-stream for a few minutes to dissolve and flush out this residue build-up.

Thanks Bathgate, I will endeavour to get my orchid under running water.