Inclusion in an Australian boulder opal - is it organic or a mineral?

[Vopros]

This is a boulder opal from Australia.

The dimensions in mm are 8 x 6 x 2.

The pictures are taken under a microscope, and the resolution is low.

in the images #1 and 3 you also could see the background, which IMO is also unusual.

I wonder if the inclusion is organic, and if not, what mineral could it be?

Thanks!

 

[Isotelus2883]

I think the probablity is that it is a botryoidal mineral growth that formed before the opal.