Our property is covered with wild raspberry, will black raspberry, and wild blackberry cane. I picked these this morning. I got about 500 ml (2 c) of berries. I've tinned them and will freeze them until I can pick more over the next few days. Then...I'll make black raspberry jam!
Maybe.
I don't know.
My wife normally makes jam but she's away for the weeks. Maybe I'll give it a go.
Black raspberries are raspberries. They have a core that comes out. Blackberries are not raspberries. They have a solid core that you can't remove. Blackberries are also normally much bigger than raspberries.