Hope you mend well, rob!
There are two rows of little carpal bones in the wrist. The scaphoid is in both and is the only rigid 'bridge' between the 'front' and 'back' rows, so it tends to crack if there's excessive shear between these rows.
To complicate matters, it has a rather fragile blood supply and good circulation is needed to ensure healing. A fracture can sever the vessel that supplies the bone, resulting in 'death' of a fragment.
But yours is apparently healing, which is good news.
I am still paranoid about the scaphoid, as I posted on Facebook...