Ny mulberry leaf look like the ones on this site. https://www.thetortoisetable.org.uk/plant-database/viewplants/?plant=257&c=4#.XMXoex5Ok0M
That is 100% a mulberry leaf. There are different varieties and at least two different mulberry species. The red and the white. I have two trees that are 50 feet apart and produce very different leaves. One of them makes leaves like the one in your picture and the other look like this:
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Here is an assortment of mulberry leaves:
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