Does anyone know what this could be?
Looks like rhodochrosite
Looks like Lepidolite to me. A Lithium rich member of the mica group.
I agree with clarkoe looks like a mica mineral, try taking a very small shaving of it use a strong magnet to see if it has any reaction , all the other micas except Lepidolite contain Iron.
Thanks I’ll give the magnet a go and let you know.