You can only see a pattern when it is acid etched. It is really hard to tell from a photo, especially from one taken so far away. Can you get a closer up shot ?
Magnetite leaves a black streak and Hematite a red streak. Both are metalic in luster. The easiest way you can test this is to take your toilet tank lid off and rub the rock on the bottom, rough surface of tile. If it leaves a red streak, its hematite, black its magnetite.