Thank you for all input. Your ideas did give me some thoughts which was:
I have taken, tooth brush, soap water, sponge/scouring pad to it. I used some Himalia sea to soft scouring pad because the granules are a bit larger then regular salt. I then washed it again.
The pictures attached (pic 1 is before work and 2 is after the work) doesn't look as it does in the "natural" in natural light. But hope you can see some difference. Again thank you for your time for reading and contributing. Maybe I will come across another idea because it seems it could be better.