How do you make the metal fragment?

First, you'll need to find metal ore. It looks almost just like the stoned scattered over the island except they are dark reddish in appearance. Like they're rusty. I have only found these on the mountain. On your map it's the grey, squarish, elevated area. There is an area that is lighter than the rest of the mountain. Go there and bring a few pickaxes. The area should be littered with several metal ore stones. Bash them like you would any old rock and collect as much metal ore as you can. Now you need to build a furnace. Once you build that, put your metal in the top slots (you can put in two batches of metal ore and they'll smelt in turn) and place wood in the appropriate slot. Light the fire and wait! Metal scraps. The furnace will also produce copper from copper ore, sulpher from that ore, and glass from scilica (the latter two are found on the wide expanse of beach seen on your map).