pink discolouration on raw timber

Hi
I need some advice for a problem I am having with new guinea rosewood doors. I installed the brand new doors about 3 months ago raw and are just getting around to sealing ready for a polyurethane coating. Most of the doors are OK but in several places there is black discolouration of the timber and when you hit it with the orbital sander the black areas it turns pink. And very pink!!
Attaching some photos to show what I mean.
WE live on the far north coast of NSW so could be a mould problem I guess. Have tried vinegar with no effect.
I tried sanding the pink areas but it seems quite deep and did not want to have depressions in the timber.

Wondered if anyone else has seen anything like this. The timber is open so I guess would favour mould but it is not the tropics only the subtropics so this has got me stumped. Another suggestion was iron oxide stains.

I guess I an after advice on whats going on and more importantly what I can do to remove the pink hue before coating.

cheers
paul

NGR has a wide range of natural colours, from a uniform light honey brown through to almost purple streaks and at times can be a fairly consistent burnt orange somewhat like African Padauk. I think you just have some that covers a range of those colours.

Out of curiosity - can you notice any insect / borer activity near the dark streaks?