Many hundreds of the silver coins from Polish find spots have been analyzed. Statistical tests are employed to test the validity of differences in fineness between mints, especially where imitations were produced. A difference between the Abbasid imitations and the true dirhams was found. Trace element correlation was not helpful, suggesting provenancing from ore sources is not possible, but there was a difference in the mercury content, that element being totally absent from the North Eastern mints, but common in the coin from the Western and Central mints.