So I was in primary school and it would have been about 1995.
The story was of a young girl who ended up going to live with a woman who taught her about Wicca the story was about her journey of learning culminating in them dressing her all in white and going on a pilgrimage for her and other girls initiation type ceremony. The woman is described as wearing purple I think for this ceremony.
I'm afraid I don't have more detail. I remember loving the story though and would love to know what book it was.