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Doesn't seem to have any identifiable meteorite characteristics and it's rather large to be slag or clinker.
Try giving it a streak test on the unglazed side of a ceramic tile. Streak firmly a few times (don't rub to-and-fro as if you're colouring in) and blow away any dust (to see the nature of the streak itself).
A meteorite will likely skid off the tile without leaving a streak (or at best a very weak, 'dirty' streak), although the absence of a streak is not a conclusive diagnostic for a meteorite. If you get any kind of deeply-coloured streak (black, grey, brown, orange or red hues), it's likely something terrestrial with a high proportion of iron oxides.