A Common Skin Problem
Many chinchillas have a condidtion I refer to as dry scale on their ears.
This is common in pale coloured chinchillas.
You will see a powdery look on their ears.
Some think this is a serious skin condition.
it may simply be a sign of dry skin.
No need for expensive lotions and creams, try a small amount of unscented baby oil rubbed in to the tip of the ear.
Do not give a a sand bath while treating or the sand will stick to their ears.
Also refrain from leaving the sand bath in their cage all the time.
Too many sand baths can dry their fur and skin out too much.
Try to reach a happy medium as regards sand baths.