How to identify unknown, insoluble solid with limited resources?

Looking for suggestions on how to identify an unknown white solid we received as a donation. It was originally labeled as $\text{MgSO}\_4$, but clearly is not. We suspect it might be $\text{CaSO}\_4$. So far, I can say that it is practically insoluble in water. We are a DIYbio lab and so were aren't equipped for complex chemical analyses. We also don't have a fume hood so we can't utilize any reactions that might produce noxious gases. Any ideas would be greatly appreciated if only so I don't have to see the bag sitting on my desk anymore.


[![enter image description here](https://i.stack.imgur.com/QYgIQ.jpg)](https://i.stack.imgur.com/QYgIQ.jpg)




Since you don't know *what* it *might* be contaminated with, it might need to be disposed as *hazardous waste*. It could be contaminated with biological material, or even with radioactive wastes, which would not show on any but the most sensitive *chemical* assay.


As the old riddle goes:


What do you call 1,000 liters of sewage mixed with 1 ml of *Chateau Mouton-Rothschild 1945*? Sewage.


What do you call 1,000 liters of *Chateau Lafite 1869* mixed with 1 ml of sewage? It's still sewage.


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