That does look a lot like black locust. But not sure. If not, that has a loooooot of sap wood. Kind of looks like mulberry, except you said it has throrns. Locust has thorns as well. If you cut it this time of year, the tree should have had horse apples. Some call them hedge apples, osage apples, spider apples, etc. etc.
If it is locust, you can still make a fine bow from it.