I'd like to help but without but without more info (or seeing it in person) it's very hard.
Where did it come from (locality)?
Are there any crystal structures visible?
How hard is it? Will your fingernail scratch it? No? Then try glass, an iron nail, quartz, i.e., move up in hardness until you see a scratch. This will give an idea of its Mohs hardness rating.
Is it hefty (heavy for its size)?
A streak test would help, both on white and black unglazed porcelain ceramic if you can manage.
What I can say is that the color (orange/brown/red) is indicative of iron staining or content.
Good luck and let us know.